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locates the light from the projector on the profile that the
roughing brush has to trace and confirms the point. Profiles
for left and right feet of the total size range are then
generated automatically. This takes only five to six minutes
and also programs in the pressure of the brush, its angle
and forward and rotational speeds at each point.
Programming the frequency and degree of re-sharpening of
the brush can also be done at the same time.
On the CD8
(Figure 2)
the self-learning system goes a step
further by adding a camera that can program roughing for
side wall sole units by automatically reading and storing a
profile drawn on the upper. If it is unable to read the traced
line clearly because of other marks on the upper, the operator
checks whether the camera is indicating an emergency sign
and, if so, locates the cursor on the screen in the correct
position. Unlike the CD1, both right and left feet of the
medium size must be programmed separately and for every
size in the range.
AUTOMATIC ROUGHING AND CEMENTING
But why stop at just roughing, why not also add cementing
and perform both operations on a single machine? While this
approach does not suit every factory, there are many where it
does and there are several machines currently available.
The RZ series from Leibrock Maschinenfabrik GmbH of
Germany demonstrates just what is possible with this type of
machine. Programming is again straightforward and can be
through a teach-in system or downloading the roughing and
cementing contours from a disc. Grading for size is automatic
and programs for different last shapes can be selected by
simply pushing a button. Good quality roughing is provided
even on different material combinations as the rotation,
downward pressure and forward speed of the brush as it
follows the prescribed contour can all be individually adjusted
as required. The inevitable change of brush diameter after
automatic sharpening is balanced automatically.
The program also controls the cementing phase in a
similar way so that a precise contour is followed and the
amount of adhesive and application speed carefully regulated
for the optimum result in terms of both accuracy and
achieving maximum bond strength to the sole. Both solvent
and water-based adhesives can be used and any harmful
vapours are drawn off within the machine itself. The reason
why this type of machine is a practical proposition lies in the
fact that the two operations have so much in common.
The question is whether to go for a twin or single station
machine. Leibrock offers both options depending on factory
requirements. The RZ 20 is equipped with two shoe boxes for
locking the shoe, allowing the two operations to be
performed simultaneously. While the shoe in one shoe box is
roughed, the shoe in the other box is cemented at the same
time and vice versa. The RZ 10, on the other hand, is
equipped with only one shoe box, where the operations of
roughing and cementing are performed one after the other
and with the shoe again locked in the box just the one time.
Machines of this type have not just replaced the demanding
skills of the hand rougher but have greatly improved the
quality and accuracy of the cementing operation. In addition,
they are faster, do not require skilled operators and, indeed,
if coupled with robots, relatively little human participation.
The choice of automatic roughing or roughing and cementing
machines now on the market covers just about every
eventuality and it is hard to see how they could possibly be
developed very much further. However, there is now an
entirely different approach in the case of roughing: do away
with the roughing brush altogether.
LASER ROUGHING
This is not an totally new idea and Italian company Brustia
demonstrated a prototype machine at SIMAC in 2006. It
created quite a stir at the time due to its speed and ability to
rough to any depth without creating dust only where wanted
on the upper. The latter aspect was attractive to sandal
manufacturers but, at the time of writing, the machine is not
available. The concept of laser roughing nevertheless has
much to be said for it.
First and foremost, once the shoe bottom contour program
has been set, a consistently flawless end result can be
reproduced indefinitely regardless of design. A laser is
practically frictionless so no re-alignment is needed during
production. As no pressure is put on the upper, seams and
changes in material have no effect on the roughing action
and, in addition, any contour can be followed.
Another advantage is the individual processing of different
materials in one upper. While a toecap made of tough leather
must be processed intensively, areas of most types of
synthetic material must be treated more carefully or not at
all. Add to this a degree of precision down to within 0.1mm
due to an extremely small beam width enables a laser to be
precisely directed along the upper.
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WORLD FOOTWEAR | MAY/JUNE 2012
Leibrock RZ 20 automatic roughing and cementing machine.
CREDIT: LEIBROCK