DESIGN OF BUTTERFLY VALVE & APPLYING GD&T TO THE PARTS & ASSEMBLY

AIM:

To design the various parts of butterfly valve and applying the GD&T to the parts and assemble the butterfly valve.

OBJECTIVE:

• To design the butterfly valve part bodies.
• To create the drafting and apply GD&T of all part body.
• To assemble the butterfly valve and apply the GD&T .

BUTTERFLY VALVE:

A Butterfly valve is a quarter-turn rotational motion valve, that is used to stop, regulate, and start a flow. Butterfly valves are easy and fast to open. A 90° rotation of the handle provides a complete closure or opening of the valve.

Parts Of Butterfly Valve's are.

1. BODY
2. SHAFT/STEM
3. RETAINER
4. DISC
5. LEVER
6. NUT 
7. SCREW

GD&T

 Here after modelling various components of the Butterfly valve, GD&T (Geometric Dimensioning & Tolerancing) is applied to each component and final assembly.Geometric Dimensioning and Tolerancing (GD&T) is a system for defining and communicating engineering tolerances. It uses a 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 American Society of Mechanical Engineers (ASME) Y14.5. This article is based on that standard, but other standards, such as those from the International Organization for Standardization (ISO), may vary slightly. The Y14.5 standard has the advantage of providing a fairly complete set of standards for GD&T in one document. The ISO standards, in comparison, typically only address a single topic at a time. 

Advantages of applying GD&T:

• Saving Money - GD&T enhances to design a 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 while ensuring 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.

PART DESIGN

1. BODY

Butterfly valves are usually fixed between two pipleines using flange couplings. Body of our Butterfly valve and GD&T applied to the same using Siemens NX CAD are shown below.

GD&T

2. SHAFT - BUTTERFLY VALVE

The shaft is the middle part of the butterfly valve and the disc/plate, lever and nut are assembled to this shaft.

3. RETAINER

The retainer is a specially shaped washer that fits over the top of the valve spring. The keepers, or locks, fit into the valve stem grooves, holding the retainer and spring in place.

4. DISC

The flow closure member of a butterfly valve is the disk. The disk is the equivalent of a plug in a plug valve, gate in a gate valve or a ball in a ball valve. Rotating the disk one-quarter turn or 90 Degrees opens and closes the butterfly valve. When valve is fully opened or closed the disc is rotated a quarter turn.Disc is mounted on shaft. 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.

5. LEVER

Lever is mounted at an end of shaft outside the body. Hand lever is usually used in small sized Butterfly valves. It is capable of being locked into a position of open, partially open, or closed.

6. NUT 

Nuts are almost always used in conjunction with a mating bolt to fasten multiple parts together. The two partners are kept together by a combination of their threads' friction.

SCREW

ASSEMBLY - BUTTERFLY VALVE

After completing the modelling of various components of butterfly valve, all parts were assembled together using Siemens NX Assembly workbench.

CONSTRAINS - ASSEMBLY

GD&T

CONCLUSION

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