EJOT SHEETtracs®
|
|
For a secure thin sheet metal joint with pre-hole The process capable assembly of pre-drilled, thin sheets has always presented a problem in the field of repeat assemblies. If a few years ago sheet metals with 1mm and more thickness were the rule, today the thickness is constantly being reduced due to cost saving potentials. Up until then the demands on the joint could sometimes still be realised with common sheet metal screws, more often though with the respective clip-on washer or preparation of the pressed hole. Assembly EJOT SHEETtracs®: 1. Application 2. Thread grooving 3. Tightening
|
Considering this reduction in thickness of the sheet metal and the adherence to DIN 7975 for sheet metal joints at the same time, the problem occurs that the thickness of the components to be joined has to correspond to the pitch of the used sheet metal screw as a minimum requirement. A repeat assembly is still oftentimes not possible, since partly only one thread is engaged in the sheet metal. Therefore the so called thin sheet metal screws have been successful in the market place in recent years. These screws have a metric 60° thread and in most cases
a conical tip. The advantage of this metric thread is the smaller pitch compared to sheet metal screws, which enables more thread engagement in the thin sheet metal.
But since most times he formed female thread -and not the screw- is the real weak spot of the joint. EJOT recognized this potential and developed a thin sheet metal screw for a process capable assembly in thin sheet metal with a pre-hole. The EJOT SHEETtracs® has a 45° (30°/15°) asymmetric flank angle and by that creates a more stable female thread in the sheet metal because of the lower material displacement. In this way the torque level of the joint is increased and a repeat assembly becomes possible.
In the lower, conical part of the screw the flank angle is turned round and thus the extrusion is formed mainly in the screw-in direction. The non-circular thread forming zone enables an easy and centred application and the increased thread area secures a safe entering into the sheet metal.
The circular cross section in the upper, bearing part of the thread results in a higher flank coverage in the sheet metal, compared to non-circular thread geometries. Thus the metric pitch of the EJOT SHEETtracs® enables a trouble free replacement, e.g. in the repair case.
Please, send us a copy of your publishing.
EJOT GmbH Geschäftsbereich Verbindungstechnik
Andreas Blecher (Marketing)
In der Bienhecke
D-57334 Bad Laasphe
Tel. +49 2752 109-118
Fax +49 2752 109-268
Internet: www.ejot.de
