Week 14 challenge

OBJECTIVE

The objective of this project is to design a butterfly valve and apply GD&T to its components and final assembly using Siemens NX.

INTRODUCTION

GEOMETRIC DIMENSIONING & TOLERANCE

• Geometrical dimension is a geometric characteristic, the size of which is specified as length angle location or Centre of distance etc.
• Tolerance on a dimension is the total permissible variation in its size, which is equal to difference between the maximum and minimum size.
• GD&T is a symbolic language used in engineering drawing. It is a symbolic language used to specify size shape orientation and location on a part.
• It is used to control dimension variation in part. So less variation means less waste
• It is used for ensuring the proper assembly of mating parts.

BODY OF BUTTERFLY VALVE

• Create two circles of the required diameter and use the Extrude command to form a cylindrical body.

• On that cylindrical body create three lugs with holes in them. This will help us connect the butterfly valve to the pipe flanges. We have created the lugs on the mid-plane and then Extruded them with reference to the mid-plane(i.e. symmetrical value).

• Using the Move object command we created similar lugs on the outer surfaces of the body with the help of lugs created earlier.

• Create a new datum plane and draw a circular sketch of the required diameter. Extrude this sketch up to the cylindrical body using the extrude command.

• Then create counterbored holes in the body using the Hole command so that we can insert shaft/stem in it. Specify all the required values of diameter and hole depth accordingly.

• Create another datum plane on the other side of this newly created feature. Develop a circular sketch on this new plane and then extrude it up to the cylindrical body.

• On the outer surface of the parent feature of the counterbored hole, create three small holes using the extrude command so that we can assemble other components to the body.

• Combine all the features to form a single object using the Unite command.

ISOMETRIC VIEW

DRAWING SHEET WITH GD&T:

SHAFT OF BUTTERFLY VALVE

• The stem of the butterfly valve may be a one-piece shaft or a two-piece design. This design consists of a one-piece shaft. The disc/plate, lever, and nut are assembled into this shaft.
• First, create a sketch that is cylindrical along with steps. That sketch must be fully constrained and closed to use the Revolve command.

• After creating the main body we have to create two rectangular slots on it.

• Then create two holes on the face of the bigger slot where the disc/plate will be attached. Then provide a chamfer on the front circular edge for better handling and safety reasons.

MODEL VIEW

DRAWING SHEET

RETAINER OF BUTTERFLY VALVE

• Retainer is nothing but a kind of washer assembled on the body of the butterfly valve.
• Create a circular sketch with an appropriate diameter. Also, create 3 holes in the sketch that will help us to fix the retainer to the body of the butterfly valve.

DRAWING SHEET

PLATE OF BUTTERFLY VALVE

• A disc is nothing but a flow-controlling/closure member of the butterfly valve which is attached to the stem/shaft. The disk is the equivalent of a plug in a plug valve, a gate in a gate valve, or a ball in a ball valve.
• Create an elliptical sketch with appropriate sizes (major & minor distance). Then put two holes along the minor axis which will be used to fix the disc to the shaft.
• Extrude the fully constrained sketch by providing suitable thickness.

MODEL VIEW

DRAWING SHEET

LEVER HANDLE OF BUTTERFLY VALVE

• Create two circular sketches with the appropriate diameters, and specify a suitable distance between them. Also, create a keyway slot in the bigger diameter sketch. Join these two sketches with a line tangent to both the circles.

• After creating the fully constrained sketch, first, extrude the circular regions and then extrude the mid-section with different thickness values.

• Then combine all the features using the Unite command. Then create a drawing sheet of the model and apply GD&T to the drawing.

MODEL VIEW

DRAWING SHEET

NUT - BUTTERFLY VALVE

• Nut is used to keep the lever and retainer intact with each other as well as the body of the butterfly valve.
• Create a polygon sketch (6sides) with suitable dimensions. Also, add a circular hole in the sketch so that it can be inserted into the shaft.

• For safety handling provide a fillet on the top edge of the nut.

MODEL VIEW

DRAWING SHEET

BUTTERFLY VALVE ASSEMBLY:

MODEL VIEW

DRAWING SHEET WITH GD&T

CONCLUSION

• Butterfly valve was successfully designed using NX cad and GD&T applied to all parts and the assembly of the Butterfly valve.