Remerciez-le!

Remerciez @Admin pour avoir partagé cet document gratuitement, de la manière la plus simple, en partageant sur les réseaux sociaux.

Page 1 of 37 Animations in Creo 3.0 ME170 Part I. Introduction & Outline Animat

Page 1 of 37 Animations in Creo 3.0 ME170 Part I. Introduction & Outline Animations provide useful demonstrations and analyses of a mechanism's motion. This document will present two ways to create a motion animation in Creo: one method utilizes snapshots, the second method uses servo motors in Creo's Mechanism package. The snapshot method is arguably the easier of the two. However, the latter method creates a smoother animation. In order to create and capture a mechanism's motion in an animation, we must first define connections that permit the movement (translation or rotation) of parts. This connection definition occurs in the assembly. The electronic dongle was assembled entirely with rigid constraints, which do not permit any motion. However, Cero can accommodate numerous motion connections. A list of Creo's motion connections is shown below. The pin connection and slider connection are the two simplest and most common mechanism connections. This document provides instructions for creating each connection. The ME 170 term project instructions state that you must have at least one motion axis in your final project. Your motion axis does not have to be a pin-type or a slider-type. These two connection instructions are provided solely as a reference. The outline of this document is as follows: • Pin Connection Definition • Slider Connection Definition • Animation with Snapshots • Animation using a Servo Motor Additional information on joint connections, Creo's mechanism capabilities, animations, and motion analyses can be found in the "Joint Connection, Mechanism, & Animation Reference" document on the ME 170 course website. Animations in Creo 3.0 ME 170 Page 2 of 37 Part II. Pin Connection Definition 1) Assemble and fully constrain the first part(s) of your assembly. A "Default" constraint is recommended for the first component of every assembly. This fixes the first part in place. Before defining a joint or motion connection, a fixed, fully-constrained part is needed to serve as a fixed reference. 2) Click the "Assemble" button to assemble a new component. 3) Select the component you would like to assemble and click "Open." 4) Select a "Pin" connection from the motion connection drop-down menu. 5) Open the "Placement" tab in the assembly ribbon. This will help guide you through the definition of the connection (image below). Animations in Creo 3.0 ME 170 Page 3 of 37 6) Notice that the connection definition is asking for "Axis alignment" references. Consequently, we will first select the axes to align. 7) Select the rotation axis for the pin connection. Note that a cylindrical surface, the axis of a coordinate system, and an actual axis can all be used to define a rotation axis. In the image below, the inner cylindrical surfaces of the hinge have been selected. 8) After selecting the rotation axes, go back to the "Placement" tab in the assembly ribbon (image below). Notice that Creo now requests that we select "Translation" constraints. The pin connection in Creo does not permit translational motion. It only permits rotation around one axis. It is a single degree-of-freedom (1 DOF) connection. The translation constraint is used to align the rotating components along the rotation axis. Animations in Creo 3.0 ME 170 Page 4 of 37 9) Select two planes or surfaces normal to the motion axis to serve as translational alignment constraints. Note that an offset or distance value can be specified for the translation constraint, so the planes or surfaces do not need to be coincident. In the hinge example, two mating surfaces have been selected to be coincident. Animations in Creo 3.0 ME 170 Page 5 of 37 10) Go back to the "Placement" tab on the assembly ribbon. Click on "Rotation Axis" to define additional useful parameters for the hinge. The parameters under the "Rotation Axis" heading govern the regeneration value and minimum, and maximum limits of motion for the hinge. If these parameters are not defined, Creo will permit unrealistic motion of the component such as that shown in the image below. 11) Select two planes to serve as angular references for the regen value and max and min limits of motion. The two upper surfaces of the hinge have been selected as shown in the image below. 12) Double click the angle in the model window and specify a regeneration value. Click the middle mouse button to confirm the new value. An angle of "90.00" has be specified in the image below. However, "90" was insufficient. The angle had to be adjusted to "-90" to yield a physically-feasible orientation. 13) Click the ">>" button in the "Placement" tab to set the current position as the regeneration position (image below). Animations in Creo 3.0 ME 170 Page 6 of 37 14) Click the "Enable regeneration value" checkbox to enable a regeneration value. If necessary (if required by your design), specify minimum and maximum limits of motion and check the checkboxes to enable these constraints. 15) Click the green checkmark to confirm your joint connection. 16) Move your newly assembled component by holding CTRL+ALT and clicking and dragging the component. Notice that the motion will stop at the defined minimum and maximum limits. If you have defined a regeneration value, click regenerate or type CTRL+G to regenerate the model to return the model to its base state. 17) NOTE: Pay particular attention to your assembly references when assembling components. Additional components which are assembled with references to moving components, may themselves become moving components. Animations in Creo 3.0 ME 170 Page 7 of 37 Part III. Slider Connection Definition 1) Click the "Assemble" button to assemble a new component. 2) Select the component you would like to assemble and click "Open." 3) Open the "Placement" tab in the assembly ribbon. This will help guide you through the definition of the connection. Notice that the connection definition is asking for "Axis alignment" definition. Consequently, we will first select the motion axes to align. Animations in Creo 3.0 ME 170 Page 8 of 37 4) Select the motion axis for the slider connection. This is the axis along which the two components will slide. Note that a cylindrical surface, the axis of a coordinate system, and an actual axis can all be used to define a motion axis. In the image below, the inner cylindrical surface of the pneumatic cylinder and the outer cylindrical surface of the shaft have been selected. 5) After selecting the rotation axes, go back to the "Placement" tab in the assembly ribbon. Notice that Creo now requests that we select "Rotation" constraints. The slider connection in Creo does not permit rotational motion. It only permits translation along one axis. It is a single degree-of-freedom (1 DOF) connection. The rotation constraint is used to align the translating components along the translation axis. 6) Select two planes or surfaces parallel to the translation axis to serve as rotational alignment constraints (image below). These two planes or surfaces will be constrained to be oriented parallel to one another. An offset angle cannot be specified for this rotation constraint. In this example, flat surfaces on the piston and the cylinder have been selected. Note that this is not a particularly realistic constraint for a pneumatic cylinder. The piston of a pneumatic cylinder is typically free to rotate about its translation axis. Consequently, Creo's "Cylinder" motion connection would be more appropriate. However, for the purposes of this example, the pneumatic cylinder will suffice. Animations in Creo 3.0 ME 170 Page 9 of 37 7) Go back to the "Placement" tab on the assembly ribbon. Click on "Translation Axis" to define additional useful parameters for the slider connection. The parameters under the "Translation Axis" heading govern the regeneration value and minimum, and maximum limits of motion for the slider connection. If these parameters are not defined, Creo will permit unrealistic motion of the component such as a piston that moves beyond its mechanical stops in the pneumatic cylinder. 8) Select two planes or surfaces to serve as translation references for the regen value and max and min limits of translational motion. These two planes or surfaces should be normal to the axis of motion. The top surfaces of the piston and cylinder have been selected for this example. Animations in Creo 3.0 ME 170 Page 10 of 37 9) Double click the distance in the model window and specify a regeneration value. Click the middle mouse button to confirm the new value. An distance of "1.00" has be specified in the image below. 10) Click the ">>" button in the "Placement" tab to set the current position as the regeneration position. 11) Click the "Enable regeneration value" checkbox to enable a regeneration value. If necessary (if required by your design), specify minimum and maximum limits of motion and check the checkboxes to enable these constraints. 12) Click the green checkmark to confirm your joint connection. Animations in Creo 3.0 ME 170 Page 11 of 37 13) Move your newly assembled component by holding CTRL+ALT and clicking and dragging the component. Notice that the motion will stop uploads/Voyage/ animation-guide.pdf