Joining sheet metal directly, quickly and simply
Innovative screwdriving system for vehicle bodywork production
Whereas in the past, steel sheets were easy to join by spot welding or resistance welding, today this is no longer economical due to the modern material mix. The automobile industry is under pressure from legal requirements to reduce CO2 emissions, use lightweight construction and consequently to find alternative joining methods. Where access to both sides of the connection point is available this can be done using rivets. If however only one side is accessible then the well-established direct screwdriving flow form principle comes into use. A flow form screw is positioned on an aluminium or steel sheet without pre-drilled holes and the screwdriving process begins. The screw is applied with a high pressure down-force and rotates at high speed, generating a frictional heat which forms a crater through which the screw’s thread passes under reduced pressure. A machined thread is created, a normal screw can also pass through in the case of repairs. After the flow passage has been formed the speed is reduced and the screw is tightened to the head connecting surface and then the final tightening of the fastener to the pre-determined parameters of torque and angle takes place. The entire procedure usually takes less than two seconds. Additional fastening elements such as nut and bolts are not required as the assembly has been optimally adjusted to the passage and thread of the screw. The screw is fixed. There is no need for preparatory drilling or punching of the component.
The screwdriving specialists DEPRAG SCHULZ GMBH u. CO. present a live show on the topic of flow form screwdriving (FFS) at this year’s AUTOMATICA from the 3rd to the 6th of June in Munich under the slogan “Sheet Metal - Direct - Screw Assembly”. In Hall A6, exhibition stand 310 development, product and processing engineers from vehicle bodywork construction departments, but also from many other braches in which sheet metal is assembled such as white goods, can gain first hand information about the next generation of FFS.
What is new?
The DEPRAG engineers have successfully developed a freely programmable gear for a torque range of up to 15 Nm and speed range of up to 8000 rpm from two gears with 15 Nm at 6000 rpm and 12 Nm at 8000 rpm. As well as reduced investment costs, this also means a reduction in processing costs as replacement expenses do not apply.
