DESIGN OF BUTTERFLY VALVE &

APPLYING GD&T TO THE PARTS & ASSEMBLY

INTRODUCTION:

Siemens NX 12:

NX, formerly known as "Unigraphics", is an advanced high-end CAD/CAM/CAE, which has been owned since 2007 by Siemens PLM Software in 2000.

It is used, among other tasks, for:

Design (parametric and direct solid/surface modeling).

Engineering analysis (static; dynamic; electro-magnetic; thermal, using the FEA method; and fluid, using the finite volume method).

Manufacturing finished design by using included machining modules.

Butterfly Valve:

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.

Applications of Butterfly Valves:

A Butterfly valve can be used in many different fluid services and they perform well in slurry applications. The following are some typical applications of Butterfly valves:

• Cooling water, air, gases, fire protection, etc.

• Slurry and similar services.

• Vacuum service.

• High-pressure and high-temperature water and steam services.

Advantages of Butterfly Valves:

• Compact design requires considerably less space, compared to other valves.

• Light in weight.

• Quick operation requires less time to open or close.

• Available in very large sizes.

• Low-pressure drop and high-pressure recovery.

Disadvantages of Butterfly Valves:

• Throttling service is limited to low differential pressure.

• Cavitation and choked flow are two potential concerns.

• Disc movement is unguided and affected by flow turbulence.

GD & T:

Geometric Dimensioning and Tolerancing (GD&T) is a system for defining and communicating engineering tolerances. It uses symbolic language on engineering drawings and computer-generated three-dimensional solid models that explicitly describe nominal geometry and its allowable variation. It tells the manufacturing staff and machines what degree of accuracy and precision is needed on each controlled feature of the part. GD&T is used to define the nominal (theoretically perfect) geometry of parts and assemblies, to define the allowable variation in form and possible size of individual features, and to define the allowable variation between features. There are several standards available worldwide that describe the symbols and define the rules used in GD&T. One such standard is the American Society of Mechanical Engineers (ASME) Y14.5

Advantages of applying GD&T: Advantages of applying GD&T:

• Saving Money - GD&T enhances design accuracy by allowing for appropriate tolerances that maximize production. For many projects, the process provides extra or bonus tolerances, further increasing cost-effectiveness.

• Offering Uniformity and Convenience - As a single, consistent language, GD&T reduces guesswork and interpretation whileensuring consistent geometries across design and manufacturing.

• Assisting Digital Design Methods — Clear, concise GD&T data is readily adaptable to digital design programs, including nearly universally used 2D and 3D CAD files.

• Ensuring Dimensional and Tolerance Requirements — By explicitly stating all design requirements, a thorough GD&T process guarantees accurate fulfillment of all dimensional and tolerance specifications.

• Providing Accurate Communication — Today’s intricate designs demand the most accurate and reliable communication. GD&T enables designers, manufacturers, and inspectors to communicate clearly with one other, saving time and making the process more efficient.

AIM :

• To design of Butterfly Valve in appropriate dimension with the application of GD&T - ASME Y14.5 2009.

• To assemble all the individual parts of the butterfly valve by assigning suitable constraints.

• To understand the concept of geometric tolerance and dimensioning.

Design and Methodology:

1.Butterfly valve body

The body is the housing for the internal components and it is the main part of the butterfly valve. The body connects to two pipes on its two sides and it regulates to flow. For the creation of this part, simple features like to revolve, extrude, and move objects are used in the modeling application of NX.

Features used to create the Butterfly Valve :

• Sketch

• Extrude

• datum plane and coordinate

• counterbore

• unite

Methodology:

Initially, Select the XY coordinate and click on the line tool from the Sketch tab.

After that sketch is Extruded, the ears of the butterfly valve are drawn and are copied on both sides of the cylindrical portion, then it is extruded.

Now a new plane is created on the surface of a cylinder using the datum plane option and a cylinder is created on that plane. then, The hole command is used to create a counterbore on that cylindrical surface.

Finally, three holes are created for mounting of the body and then, the part is saved.

2.Shaft

It is another important component of the butterfly valve. It inserts into the body of the valve and sits perpendicular to the direction of flow. It holds the disc inside the body and is clamped with the lever outside the body. It is created using simple features like revolve and extrudes features in the NX modeling environment. After the part creation is completed, the drawing is created in the drafting application of NX, and GD&T is applied using the features of NX. For this shaft, position tolerance should be given to the holes which hold the disc, a profile of the surface should be applied to the surface where the disc sits, and position tolerance for the cylindrical body of the shaft concerning the defined datums. Composite position tolerance is applied in the case of disc positioning holes as it repeats creating a pattern.

Features used to create Shaft :

• Sketch

• Revolve

• Datum plane

• Extrude

• Chamfer

Methodology:

Initially, Select the XY coordinate and click on the line tool from the Sketch tab.

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 are created in the rear recess portion of the shaft.

3. Disc Plate

This disc plate is the main component of the butterfly valve which regulates the flow in the valve. The orientation of this disc determines the flow rate of the fluid. It is not perfectly circular, rather it is elliptical in profile. The holes in it help to position it properly on the shaft created earlier. A simple feature like extrude can create this part in NX. To apply GD&T for this part, the primary datum is defined on the surface where it comes in contact with the surface of the shaft, and perpendicular and perpendicular tolerances are applied as per the requirement. As the cost increases, while machining the entire contact surface, small circular datum targets are created and GD&T is applied to reduce the manufacturing cost.

Features used to create Shaft:

Sketch

Extrude

4. Lever

A lever is a handle that is used to rotate to regulate the flow. It is attached to the shaft with the help of a key to fixing it in position concerning it. So when it is rotated, the shaft rotates which in turn rotates the disc and regulates the flow inside the pipe. It is createdusing simple features like extrude in NX after the proper base sketch is created. For the application of GD&T on the lever, a section view is also created to show how different datums are defined and tolerances are provided. Position tolerance is applied to the proper holes after the perpendicular tolerance is applied to the first hole. To control the key slot, small tolerance is applied to the width of it. Profile

tolerances are provided to the surfaces which come to contact with other parts as per the requirement.

Features used to create Shaft :

• Sketch

• Extrude

Methodology:

With the help of 2D drawing of the lever, the 3D model of the lever is designed with the help of different operations.

The different operations used are Trim, Extrude, circle, Tangency, etc.

Finally, the part is saved in the required folder.

5. Retainer

This part helps to retain or to fix the shaft with the body of the butterfly valve. It prevents the shaft from coming out of the body and keeps it in position for the proper functioning of the disc inside the body. The creation of the retainer plate involves only a simplefeature like extrude in NX. For the GD&T application in the retainer plate, similar steps are followed as in the case of the disc. Primary, secondary and tertiary datums are defined properly as per the design intent, and datum targets are applied to the holes. Perpendicular and position tolerances are applied to lock the DOF of the retainer in position. A profile tolerance is also applied to control the upper

surface of the retainer.

Features used to create Shaft :

• Sketch

• Extrude

Methodology:

The 3D model of the Retainer is created with the help of given dimensions.

Initially, the concentric holes of 200mm and 56mm diameter are drawn and the other 3 circles of 20.3 mm diameter are drawn with the help of 150mmBCD by using the Pattern option.

Finally, the 2D sketch is extruded and the part is saved in the required folder.

6. Nut:

It is the last part that helps to fix the lever in position with the stem. It allows to keep it in position or to disassemble whenever required. It is created using simple extrude and revolve features in NX. To apply GD&T for this nut, the primary datum is defined on the surface which comes in contact with the lever. Perpendicular tolerance is applied to the hole or the thread and is defined as datum B. Size tolerance is also applied to the thickness of the nut.

Features used to create Shaft :

• Sketch

• Extrude

• Revolve

Methodology:

The 3D modeling of the Nut is created with the given dimensions.

Initially, the hexagonal shaped nut is extruded with a depth of 25mm and a hole of 37mm diameter.

Finally, the fillet of radius 10mm is provided by using the revolve op

7. SCREW:

A nail-shaped or rod-shaped piece with a spiral groove and a slotted or recessed head designed to be inserted into material by rotating (as with a screwdriver) and used for fastening pieces of solid material together.

After the design, all the models should assemble with appropriate constraints. The assembly is created by first placing the body in position and mating other parts to it with the application of different joints provided in NX. First, the shaft and disc are joined together with the screws in place to create a sub-assembly which is then joined to the body in position. The retainer plate is then mated with the body and screws are used to fix them. After that, the lever is mated to the shaft in a position that is then fixed after the nut is mated with the shaft.

Features used to Assembly:

• Infer Axis/center

• Touch Align

• Concentric

• Move Component

Methodology:

The Assembly file is opened in NX CAD.

The above parts are added to the assembly file.

Now, one by one part is assembled using the Move part command and assembly constraint command.

Different constraints are used to assemble butterfly valve, such constraints are Infer Axis, Touch, Align.

Finally, the assembly of the butterfly valve is saved in the folder where all the other parts are saved.

CONCLUSION:

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