Week 14 challenge

BUTTERFLY VALVE ASSEMBLY AND APPLYING GD&T TO THE ASSEMBLY

Aim

The aim of this project is to design a butterfly valve assembly and to apply GD&T to the parts and to the entire assembly.

Butterfly Valve

Fig 1. Butterfly valve.

Butterfly valves are a family of quarter turn rotational motion valves that are used in pipelines to shut-off flow. It is often said that butterfly valves can be used to regulate the flow. However, doing this can damage the valve disk and can have negative effect on the sealing properties. They are used in a wide variety of industries especially in water supply, collection and distribution, as well as pumping stations, and have a broad range of use cases especially in flow isolation. Their key advantages are their simple construction and compactness.

Parts of Butterfly valve

• Butterfly valve body
• Shaft
• Retainer
• Disc
• Lever
• Nut
• Screw

Initially the modelling of all these parts were done and GD&T was applied to the individual parts. Then they are assembled together by providing the required assembly constraints and GD&T is applied to the assembly. The software used is Siemens NX.

Butterfly valve body

Fig 2&3. Different views of butterfly valve body design.

Shaft

Fig 4. Shaft design.

Fig 5&6. GD&T is applied to shaft.

Retainer

Fig 7. Retainer design.

Fig 8. GD&T is applied to retainer.

Disc

Fig 9. Disc design.

Fig 10. GD&T is applied for disk.

Lever

Fig 11. Lever design.

Fig 12. GD&T is applied to lever.

Nut

Fig 13. Nut design

Fig 14. GD&T is applied to the nut.

Screw

Fig 15. Screw design.

Assembly

The initial step for assembling the parts is to create an assembly file in the folder where all the part files are saved. Then each part is introduced into the workbench using Add Component command. Then the parts are moved to the respective positions using Move Component command and proper constraints are given for assembling the parts with each other.

Fig 16. Feature Tree containing the assembly file and part files.

Fig 17. Given constraints.

Fig 18-21. Different views of butterfly valve assembly.

Drafting of assembly

Fig 22. GD&T is applied to the assembly.

• For the assembly, GD&T is applied according to the fluid flow direction. The fluid flows through the large central hole of the butterfly valve.
• From the design, it is understood that the three ear like parts on both sides are the ones that comes in contact with the external pipeline. So one of the faces that containing the holes are taken as A datum.
• For A datum, we use datum target areas A1, A2 and A3 at the regions of the holes and each region is given a flatness tolerance of 0.25.
• Among the three holes, one is taken as B datum. It is given a perpendicularity tolerance of 0.25 at MMC with respect to A datum.
• The other hole is taken as C datum and it is given a position tolerance of 0.25 at MMC with respect to datums A and B.
• The 3rd hole is given a position tolerance of 0.5 at MMC with respect to datums A, B and C.
• There are 3 other similar holes exactly opposite to the 3 holes which was considered just now. So they should be perfectly aligned with the holes that were already given GD&T.
• In order to give the perfect alignment, the 3rd hole among the first 3 holes is taken as datum D in order to alingn the hole opposite to it with respect to D datum. The opposite hole is given a position tolerance of 0.75 at MMC with respect to datum D.
• Similarly holes opposite to B datum and C datum were also given position tolerance of 0.75 at MMC with respect to B datum and C datum respectively.
• The face containing the 3 opposite holes were given a profile of a surface tolerance with respect to A, B and C datums.
• The central large hole, through which the fluid flows is given a position tolerance of 0.5 at MMC with respect to A, B and C datums.

Fig 23. Drawing sheet.

Thank you.