UK-based Self Pierce Rivet manufacturer Henrob , is in the final stages of putting together a robotic assembly cell for the production of a car sunroof application.
The entire cell has been designed and developed at Henrob’s Deeside plant in Flintshire. The cell consists of an ABB robot, a Henrob hydraulically powered riveting system, with tape fed rivets and a bespoke pneumatic turntable to place the sunroof components prior to riveting.
As one sunroof is being riveted together an operative 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 whole cell has been developed to produce two variants of the sunroof as the OEM will use the sunroof design on two different vehicles. It is estimated that 120,000 units will be built per year, with 8 self pierce rivets per assembly.
The OEM specified Self Pierce Rivets (SPR) because of the strength characteristics they can offer and their ability to join dissimilar materials, in the case of the sunroof the assembly is joining 2.0mm aluminium to 1.0mm steel.
In addition to these benefits, as SPR does not need a pre-hole, it eliminated drilling, swarf and alignment issues.
SPR does not create heat, sparks or fumes and is a low noise, environmentally friendly process.
SPR is not only used in the automotive sector, SPRs increasingly feature in a wide range of industries, as manufacturers face the challenges of more extensive use of new materials like aluminium, 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 self-pierce rivet is driven into the material to be joined at high force, piercing the top sheets of material spreading outwards into the bottom sheet of material, under the influence of an upsetting die, to form a strong joint.
It is a process requiring no holes that delivers high static strength similar to or better than spot welding. The process produces a fatigue resistant joint that is up to 30% stronger than spot welding. Cycle time is two to four seconds.
Henrob has a range of tool configurations and types of rivet to suit the wide possible range of general industry applications, with customers ranging from roadsign manufacturers, light steel frame buildings, heating and ventilation and white goods.
The robotic cell is due to be installed at the customer’s premises in April.