SHS Jointing, Flowdrill & Hollo-Bolt - Tata Steel

Flowdrill
Flowdrill
The
Process
Flowdrilling is basically a thermal drilling
process which makes a hole through the
wall of a structural hollow section without
the removal of metal normally associated
with a drilling process. The formed hole is
then threaded by the use of a roll thread
forming tool, leaving a threaded hole which
will accept a standard fully threaded bolt.
The Tools
The initial hole is made by a Flowdrill tool
consisting of a tungsten carbide bit held in a
Flowdrill Morsetaper collet adaptor (Fig. 1). The
tool can be used in a conventional drilling
machine or CNC machine as found in
fabricators works, provided it has adequate
horsepower and spindle speed.
1st stage
The tungsten carbide bit is brought into contact
with the RHS wall where it generates sufficient
heat to soften the steel. The bit is then
advanced through the wall and in so doing the
metal is redistributed (or flows) to form an
internal bush. As well as drilling the initial hole,
the tool is fitted with the means of removing any
surplus material which may arise on the outside
of the RHS section. The cycle time for
Flowdrilling is similar to that for conventional
drilling. However, if done on CNC machines the
feed rate can be slow at the beginning, rapidly
increasing as the material softens to improve
efficiency.
2nd stage
The 2nd and final stage is to tap the Flowdrill
bush. This is done by roll threading the bush
with a Coldform Flowtap. The complete cycle is
shown in Figure 2.
Fig. 2
Tool holder
Flowdrill data :
The Flowdrill system was developed by Flowdrill BV in Holland, and is available in the UK from
their agent - Robert Speck Ltd,. Little Ridge, Whittlebury Road, Silverstone, Northants NN12 8UD.
Tel: 01327 857307 Contact Mr Mike Carpenter.
Fig. 1
Collet
Flowdrill bit
1st Stage 2nd Stage