Designing and Assembly of Butterfly Valve using NX CAD

Aim :- To model and assemble Butterfly Valve and apply GD&T to the butterfly Valve.

Introduction:-

A butterfly valve is a valve that isolates or regulates the flow of a fluid. The closing mechanism is a disk that rotates.

A butterfly valve is from a family of valves called quarter-turn valves. In operation, the valve is fully open or closed when the disc is rotated a quarter turn. The "butterfly" is a metal disc mounted on a rod. When the valve is closed, the disc is turned so that it completely blocks off the passageway. When the valve is fully open, the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the fluid. The valve may also be opened incrementally to throttle flow.

Procedure:-

For modeling and assembly of butterfly valve different parts of butterfly valve was designed such as

• Body
• Shaft
• Disc plate
• Retainer
• Lever
• Nut
• Screw

For modeling above parts different Commands were used such as

• SKetch:- Sketch is used to creat a 2D drawing which is later used to form 3D model.
• Extrude:- It extrudes the sketch or selected sketch contours in one or two directions to creat a solid feature.
• Hole:- A Hole feature is used to create holes on the model.
• Unite:- Unite is used to convert two or more solid bodies into one solid body.
• Revolve:- It revolves a sketch or selected sketch contours around an axis to create a solid feature.
• Chamfer:- Chamfer is used to connect two adjacent faces using an inclined line.

Overview of parts of Butterfly valve:

1] Body of butterfly valve

• Initially, the sketch for the body of butterfly valve is drawn using the sketching tools in NX CAD.
• After that sketch is Extruded, then ears of the butterfly valve is drawn and is copied on both sides of the cylindrical portion, then it is extruded.
• Now a new plane is crated on the surface of cylinder using datum plane option and cylinder is created on that plane. then, Hole command is used to create a counter bore on that cylinderical surface.
• Finally, three holes are created for mounting of the body and then, the part is saved.

2] Shaft

• Sketch is created on a plane then, Revolve command is used to get the desired shape of the shaft.
• Then Extrude command is used to create a recess portion in the front and rear portion of the shaft.
• Finally, two holes of 12.5mm diameter is created in the rear recess portion of the shaft.

Drafting of shaft:

• A1 size of sheet is used create drawing of shaft.
• Here, only two datums are used as one degree of freedom is required for efficient working of the shaft.
• Datum A1 and A2 is given to the part which comes in contact with the body of butterfly valve.
• Datum B is given to the base of the shaft.
• Different tolerances are given to some features which are important for functioning of the shaft.

3] Disc Plate

• 2D sketch is created on a plane as per the given dimensions.
• Then, the sketch is Extruded create Disc plate.

Drafting of Disc plate

• Datum target areas A1 and A2 is given to the side of the disc which is going to come in the contact with shaft.
• This two datum target area A1 and A2 forms datum A.
• Datum B is given to the one hole on the disc plate and Datum C is given to the other hole.
• Then, the tolerances are given to the surface and features of the Disc plate.

4] Retainer

• 2D sketch is drawn on a plane.
• Then the sketch is Extruded to create a Retainer.

Drafting of Retainer

• After modeling, drafting tool is used to create a drwaing of retainer on A1 size drawing sheet.
• Datum target area A1,A2 and A3 is given to the surface which comes in the contact with the upper surface of body.
• Datum B is applied to the one of the holes of retainer where the screw is inserted.
• Datum C is applied to the other hole.
• Finally, other tolerances are applied to the surfaces and features of retainer.

5] Lever

• 2d sketch is created on plane with the provided dimensions.
• sketch is then Extruded to create Lever.

Drafting of Lever

• Datum A is given to bottom surface which comes in contact with retainer.
• Datum B is given to the hole where the bolt is to be inserted.
• Datum C is given to the other hole to complete the constraint the part.
• Finally, other tolerances are applied to the surfaces and features of Lever.

6] Nut

• A hexagon is created on the plane and is then extruded to get desired solid body.
• Another sketch is created on XZ plane, Sketch fillet is used to create a arc which will gives smooth curve to the upper surface of Nut.

Drafting of Nut

• Datum A is given to the bottom surface of Nut which is going to come in contact with Lever surface.
• Datum B is given to the Hole.
• Finally, other tolerances are given to the surfaces and feature of Nut.

7] Screw

• 2D sketch is created on a plane as per the given dimensions.
• Then, revolve command is used to create a screw and the part is saved.

8] Assembly of Butterfly Valve

• Assembly file is opened in NX CAD.
• Above parts are added in the assembly file.
• Now, one by one parts are assembled using Move part command and assembly constraint command.
• Different constraints are used to assemble butterfly valve, such contraints are: Infer Axis, Touch, Align.
• Finally, assembly of BUtterfly vlave is saved in the folder where all the other parts are saved.

Drafting of Assembly

• Datum target area A1,A2 and A3 is given to the ears of the butterfly valve.
• Datum target area A2 and A3 is given with perpendicular tolerance and Position tolerance respectively.
• Sub datum D is given to the thrid ear.
• Finally, other tolerances are given to the surfaces and features of the Butterfly Valve.

Conclusion:-

Designing and Modelling and drafting of different parts and assembly of Butterfly Valve is completed.

Part and Assembly file:-

https://drive.google.com/file/d/1Eu09KkHC8iQjzgJqKUsb7Lt6yBcEBIWR/view?usp=sharing