Nit Pop Nit

Nitul este un organ de mașinã utilizat la realizarea îmbinãrilor nedemontabile indirecte
Un nit este format dintr-o tijã cilindricã (care poate fi tubularã) și un cap inițial. Un al doilea cap, numit cap de închidere, se formeazã în urma operației de nituire. Nituirea se poate realiza manual sau mecanizat.
Clasificare
dupã forma capului
nituri cu cap semirotund
nituri cu cap cilindric
nituri cu cap tronconic înecat
nituri cu cap semiînecat
nituri cu cap tronconic
nituri tubulare
popnituri
nituri cu cap de închidere realizat prin explozie
nituri tip pocnit cu cap de inchidere tip "floare"
Sursa: WIKIPEDIA

SA nu va mai aud cu "pocnituri"


POP este marca inregistrata al firmei Emhart Teknologies
Pop niturile sunt nituri tubulate cu o tija pe mijloc


Blind rivets
Three aluminium blind rivets: 1/8", 3/32", and 1/16"

Blind rivets, commonly referred to as pop rivets, (POP is the registered brand name of the original blind rivet manufacturer owned by Emhart Teknologies) are tubular and are supplied with a mandrel through the center. The rivet assembly is inserted into a hole drilled through the parts to be joined and a specially designed tool is used to draw the mandrel into the rivet. This expands the blind end of the rivet and then the mandrel snaps off. These types of blind rivets have non-locking mandrels and are sometimes avoided for critical structural joints because the mandrels may fall out, due to vibration or other reasons, leaving a hollow rivet that will have a significantly lower load carrying capability than solid rivets. Furthermore, because of the mandrel they are more prone to failure from corrosion and vibration. Unlike solid rivets, blind rivets can be inserted and fully installed in a joint from only one side of a part or structure, "blind" to the opposite side.[2]

Prior to the adoption of blind rivets, installation of a solid rivet typically required access to both sides of the assembly: a rivet hammer on one side and a bucking bar on the other side. In 1916 Royal Navy reservist and engineer Hamilton Neil Wylie filed a patent for an "improved means of closing tubular rivets" (granted May 1917).[3] In 1922 Wylie joined the British aircraft manufacturer Armstrong-Whitworth Ltd to advise on metal construction techniques; here he continued to develop his rivet design with a further 1927 patent[4] that incorporated the pull through mandrel, and allowed the rivet to be used 'blind'. By 1928 the George Tucker Eyelet company were producing a 'cup' rivet based on the design which required a separate GKN mandrel and the rivet body to be hand assembled prior to use for the building of the Siskin III aircraft. Together with Armstrong-Whitworth, the Geo. Tucker Co. further modified the rivet design to produce a one piece unit incorporating mandrel and rivet.[5] This product was later developed in Aluminium and trademarked as the 'POP' rivet. The United Shoe Machinery Co. produced the design in the US as inventors such as Carl Cherry and Lou Huck experimented with other techniques for expanding solid rivets.

Due to this feature, blind rivets are mainly used when access to the joint is only available from one side. The rivet is placed in a drilled hole and is set by pulling the mandrel head into the rivet body, expanding the rivet body and causing it to flare against the reverse side. As the head of the mandrel reaches the face of the blind side material, the pulling force is resisted, and at a predetermined force, the mandrel will snap at its break point, also called "Blind Setting". A tight joint formed by the rivet body remains, the head of the mandrel remains encapsulated at the blind side, although variations of this are available, and the mandrel stem is ejected.

They are available in flat head, countersunk head, and modified flush head with standard diameters of 1/8, 5/32 and 3/16 inch. Blind rivets are made from soft aluminum alloy, steel (including stainless steel), copper, and Monel.

There are also structural blind rivet, which are designed to take shear and tensile loads.[6]

The rivet body is normally manufactured using one of three methods:
Name Description
Wire the most common method
Tube common in longer lengths, not normally as strong as wire
Sheet least popular and generally the weakest option

There is a vast array of specialty blind rivets that are suited for high strength or plastic applications. Typical types include:
Name Description
TriFold a rivet that splits into three equal legs like a molly bolt. Typically used in soft plastics where a wide footprint is needed at the rear surface. Used in automotive interiors and vinyl fences.
Structural rivet(a) an "external" mechanically locked structural blind rivet that is used where a watertight, vibration resistant connection is of importance. Typically used in manufacture or repair of truck bodies. A special nose piece is required to apply this rivet.
Structural rivet(b) an "internal" mechanically locked structural blind rivet that is used where a watertight, vibration resistant connection is of importance. Typically used in manufacture or repair of truck bodies.

Internally and externally locked structural blind rivets can be used in aircraft applications because, unlike other types of blind rivets, the locked mandrels cannot fall out and are water tight. Since the mandrel is locked into place they have the same or greater load carrying capacity as solid rivets and may be used to replace solid rivets on all but the most critical stressed aircraft structures.

The typical assembly process requires the operator to install the rivet in the nose of the tool by hand then actuate the tool. However, in recent years automated riveting systems have become popular in an effort to reduce assembly costs and repetitive disorders. The cost of such tools range from US$1,500 for autofeed pneumatics to US$50,000 for fully robotic systems.

Imagine: