Self-piercing rivet seeks wider horizons01 July 2008The self-piercing rivet seems to be finding acceptance in a very wide range of industries, thanks to its ability to join dissimilar materials of different thickness in a safe, quiet and environmentally friendly way. The highly automated insertion and jointing process has been perfected by automotive industry suppliers, such as HenrobSelf piercing rivet specialist, Henrob is in the final stages of putting together a robotic assembly cell for a manufacturer of car sunroofs. The entire cell was designed and built at Henrob’s Deeside plant in Flintshire, and comprises an ABB robot, a Henrob hydraulically powered riveting system (with tape fed rivets) and a bespoke pneumatic turntable on which the sunroof components are placed prior to riveting.
As one sunroof is being riveted together the operator has time to remove a completed assembly from the turntable and re-load the jig with the next set of components ready for the next assembly cycle. The cell is designed to produce two variants of the sunroof, as the OEM will be supplying the components for two different vehicles. It is estimated that 120,000 units will be built per year, each requiring eight self-pierce rivets (SPRs) per assembly.
The OEM specified SPRs for this application because they offer superior joint strength characteristics. Moreover, they are able to join dissimilar materials; in the case of the sunroof assembly this involves joining 2.0mm thick aluminium to a 1.0mm thick steel substrate. In addition to these benefits, as the SPR does not require any pre-machining, it avoids the need for drilling and all the attendant issues of swarf and component alignment. Additionally, the SPR does not create heat, sparks or fumes and the whole jointing process is quiet, safe and environmentally friendly.
The robotic cell was installed at the OEM’s premises in April of this year.
Wider uses
SPR jointing technology is not only used in the automotive sector. Increasingly SPR features in a wide range of industries, as manufacturers face the challenges posed by the jointing of ‘new’ materials such as aluminium alloys, magnesium, high-strength steels and composites. The SPR process can join sheets of dissimilar materials, like aluminium to steel, aluminium to magnesium, steel to steel and metals to composites.
During the process, the SPR delivery barrel and die are clamped to the materials to be joined. The rivet is delivered and driven with a high degree of force into the top sheet of material, piercing it and spreading a quantity of it outwards into the bottom sheet of material against the die, to form a strong and permanent joint.
It is a process requiring no pre-drilling that delivers high static strength - similar to, or better than, spot welding. Indeed, the process produces a fatigue resistant joint that is up to 30% stronger than a spot welded joint, and the cycle time is just two to four seconds.
Henrob has a range of tool configurations and rivet types to suit a variety of general industry applications, with customers ranging from road sign manufacturers, light steel frame buildings, heating & ventilation equipment and white goods.Contact Details and Archive...Related Articles...Most Viewed Articles...<< Back to company search results
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