Challenge

BUTTER FLY VALVE DESIGN AND ASSEMBLY

AAtishay Jain23 Dec 2022

ASSEMBLY AND GD&T APPLICATION ON BUTTERFLY VALVE

OBJECTIVE : The objective of this project is to design a butterfly valve and apply GD&T to it's components and final assembly using CATIA V5 .

INTRODUCTION:

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 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. The valve may also be opened incrementally to throttle flow.There are different kinds of butterfly valves, each adapted for different pressures and different usage.

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 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 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.

3-2-1 PRINCIPLE:

The 3-2-1 method is a work-holding principle where three pins are located on the 1st principle plane, i.e., either XY, YZ, ZX. And two pins are located on the 2nd plane perpendicular to the 1st plane, and at last, one pin on the plane is mutually perpendicular to the 1st and 2nd planes.

A work-piece free in space can move in an infinite number of directions. For analysis, this motion can be broken down into 12 directional movements or "degrees of freedom". All 12 degrees of freedom must be restricted to ensure proper referencing of a work-piece.

As shown in image below, the 12 degrees of freedom all relate to the central axis of the work-piece. Notice the 6 axial degrees and 6 radial degrees of freedom. The axial degrees of freedom permit straight-line movement in both directions along the 3-principle axis shown as X, Y & Z. The radial degrees of freedom permit rotational movement, in both clockwise & counter clockwise radial directions around the same three axes.

Degrees of Freedom of a Rigid Body

Consider the rigid body shown below which is situated in space. It can have 12 degrees of freedom.

COMPONENTS OF BUTTERFLY VALVE-

Various components of butterfly valve and GD&T applied to them are shown below.

1) BODY - BUTTERFLY VALVE:

Butterfly valves are usually fixed between two pipleines using flange couplings. Body of our Butterfly valve and GD&T applied to the same using CATIA V5 are shown below.

2) SHAFT - BUTTERFLY VALVE:

The disc/plate, lever and nut are assembled to this shaft.

3) DISC - 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.

4) LEVER - BUTTERFLY VALVE:

Lever is mounted at an end of shaft outside the body. Hand lever is usually used in small sized Butterfly valves. It is used to open or close the valve.