Description Of Operating Sequence - strapex SMA 20 Mode D'emploi

5.2.1 DESCRIPTION OF OPERATING SEQUENCE

The operational sequence relates to automatic strap-
ping. The designations of the clutches and proximity
switches refer to the electrical diagram on page 51
and the functional diagram on page 53.
Prerequisites
– Machine switched on
– Strap advanced
– Heating element is hot
a) Strap take-up and tensioning
After the strap is manually placed round the package
the strap start should be placed into the sealing head.
There the proximity switch B4 „Strapping start" is ac-
tivated. By reason of this, the electromagnetic clutch
Y1 operates.
By means of a cam and a tappet the right-hand clamp
is moved upwards. This causes the strap to be clam-
ped. Over the same cam after clamping the proximity
switch B1 „Aggregate" is activated. The electromagne-
tic clutch Y1 is switched off and at the same time the
electromagnetic clutch Y2 is activated. Owing to this
the tensioning belt is moved in the return direction and
the strap is tensioned. When the preset tension has
been reached (no more impulse at proximity switch
B3) the electromagnetic clutch Y1 „Aggregate" is
activated again.
b) Strap cut off and welding
A cam is turned by means of the worm drive, causing
a tappet of the left clamp to be driven upwards, and
the strap is clamped. After clamping, the same cam
activates the proximity switch B2 „Strap tension re-
lease". The electro-magnetic clutch Y2 is switched off.
Owing to this the strap is no longer under tension from
the tensioning belt.
02.11
After the left clamp has reached the clamping position,
the hot heating element is swivelled in between the
straps by means of a cam. In this way the straps are
heated. Then, by means of another cam and a tappet
the central clamp is driven upwards and the strap is
cut.
Subsequently the central clamp is driven downwards
a certain distance, the heating element is swivelled
out and the central clamp is moved upwards again. By
this process the heated straps are pressed together
and thus they heat seal themselves.
After the welding process all three clamps are moved
downwards. The sliding plate is drawn back and the
welded strap is released. Then the sliding plate moves
forward again. When the three clamps are in the
lower position, and the sliding plate has been moved
forward again, the sealing unit is in the 0° position
(starting position).
c) Strap feed
In the 0° position the proximity switch B1 „Aggregate"
is activated and the electromagnetic clutch Y3 opera-
tes. The strap is feed to the preset length.
Strapex SMA 20
23