Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02267813 1999-04-O1
The invention relates to the application of protective films
to motor vehicles.
It a.s known to apply synthetic plastic film treated on one
side with low tack adhesive to upwardly facing panels such as
hoods, trunk lids and roofs of new motor vehicles during
finishing and delivery so as to protect such vulnerable
panels from damage. Typically such film has been applied
manually but desirably such application should be effected
automatically if this can be carried out reliably and
economically.
It is an object of this invention to provide apparatus for
achieving such automation.
According to the invention apparatus for applying protective
tack film having tack and non-tack surfaces to upward facing
panels of vehicles comprises an applicator unit suspended for
vertical movement above a path of movement of a vehicle to be
protected, the unit including a primary applicator roll
engaging the non-tack surface of the film and extending
transversely of the unit so as to apply the film to an upper
surface of the vehicle as it moves along said path, means to
apply vertical movement to the unit, and means sensing upward
pressure applied to the unit through the applicator roll to
control the vertical movement application means to maintain
substantially constant pressure between the applicator roll
and the vehicle, and means to provide tack film from a supply
roll to the applicator unit: the applicator unit further
including a drive roll driven by a motor to draw tack film
from the supply roll, a perforator to form lines of weakness
across the film drawn from the supply roll at predetermined
locations, a vacuum manifold arranged to apply vacuum to
points distributed over an outside surface of the roll in
contact with said tack film to hold the latter against the
roll, and means to halt the film as a line of weakness formed
by the perforator passes over the applicator roll, whereby to
detach a length of film applied to the vehicle along the line
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of weakness while leaving the end of the film from which the
length was detached held to the applicator roll.
In an alternative arrangement, the perforator is omitted, and
instead of halting the film to break it at the perforation,
means is provided to cut the film downstream of the
applicator roll when an appropriate length has been
dispensed.
Preferably one or more secondary transverse applicator
rollers are disposed on the applicator unit downstream of the
primary applicator roll relative to the path of movement of
the vehicle, the secondary applicator rollers being idler
rollers vertically moveable at at least one end so as to
accommodate their attitude to a profile of panels to which
film is to be applied.
Preferably also a further roll is provided downstream of the
drive roll to provide a control loop in the film, together
with means to sense the size of the loop and control the
drive roll motor.
Preferably also the means to provide tack film from a supply
roll includes means to change supply rolls as the film from
one supply roll is exhausted without interrupting the supply
of film to the applicator unit.
Further features of the invention will be apparent from the
following description of a presently preferred embodiment of
the invention with reference to the accompanying drawings, in
which:
Figure 1 is a front elevation of the apparatus, as seen from
the front of an approaching vehicle, with certain parts
omitted;
Figure 2 is a side elevation of the apparatus;
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Figure 3 is a fragmentary view illustrating an exemplary
arrangement of secondary application rollers;
Figure 4 is a side elevation of preferred means to supply
tack film; and
Figures 5-8 are further side elevations of the supply means
illustrating initial threading and how the supply rolls are
changed.
Referring to Figures 1 and 2, side stands 2 form a portal
through which automobiles to be protected are advanced.
Suspended from an overhead support frame 4 is an applicator
unit 6 which is guided by the side stands for vertical
movement. At the bottom of the unit is a primary applicator
roller 8 which in its lowest position will contact an
advancing vehicle and roll over its upwardly facing surfaces .
The roller 8 is supported through load cells 10 which send
signals to a programmable logic controller (PLC) (not shown)
which in turn controls actuators 12, acting between the frame
4 and the unit 6, which lift and lower the applicator unit to
maintain the pressure applied to the roller by the vehicle at
a substantially constant level, in known manner.
Supported adjacent the unit 6 is a film dispensing unit 14
from which a protective tack film 16 may be drawn as
required. The dispensing unit is described in more detail
below with reference to Figures 4-9. The film has a tack
layer on one side (the supper side as seen leaving the unit
14). Film is drawn from the unit 14 by drive rolls 18 in the
unit 6, driven by a motor 20. Rather than pinch rollers as
shown, a roller with a non-conductive surface may be used to
grip the film through static electricity generated as the
film is driven off the supply roll. Film from the feed
rollers is fed into a control loop 22, the amount of film in
the loop being sensed by an ultrasonic sensor 24 which turns
on the motor 20 as required to maintain the size of the loop
between predetermined limits. At the exit of the loop is a
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further roll 26 associated with a pinch bar 28 which can be
forced against the roll 26 associated with a pinch bar 28
which can be forced against the roll 26 by an actuator (not
shown) to hold the film static. The actuator may be
controlled by the PLC referred to above to brake or release
the film.
The film passes downward from the roller 26 through a
perforator formed by a brush roll 30 and a rotary knife with
a discontinuous blade 31 which can be rotated under control
of the PLC to bring the blade against the brush roll and
perforate the film transversely at selected points along its
length. The film then passes downward on to the periphery of
the applicator roller 8 with its non-tack side towards the
roller. The roller 8 is perforated and provided with a non-
rotating internal vacuum manifold which applies vacuum to the
film through the perforations of that part of the roll
between the point where it is contacted by the descending
film and the lowest point of the roller. Other arrangements
for applying vacuum to the surface of the roller could
utilized.
As a vehicle approaches the apparatus (from the left as seen
in Figure 2), and assuming that its hood is to be protected,
the forward edge of the hood will contact the roller 6, or
more precisely, the tack surface of the film held by vacuum
against the roller, causing the film to adhere to the hood
and be drawn forward by the vehicle under the roller (the
pinch bar 28 is released at this point). The movement of the
film drawn by the roller is monitored, and when a point on
the film spaced from its free end by a distance just greater
than the length of the hood is passing the rotary knife, the
latter is actuated to perforate the film across its width.
When the film has moved to a point at which the perforation
is leaving the roller 6, the pinch bar is used to halt the
film, causing it to break at the perforations just downstream
of the primary application roller 6. In an alternative
arrangement, the perforator is omitted, and a knife or
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possibly a heated wire is actuated to sever the film just
upstream of the end of the panel and downstream of the roll
6.
The same apparatus may be used to apply further sheets of
film to further panels of the same vehicle. For example, the
controller may be programmed using input from appropriate
sensors to lift the applicator unit as the film is severed,
either until the roller 6 contacts the front end of a roof
panel, if film is to be applied thereto, or until the unit
is lifted over the roof panel, the unit then being lowered on
to the leading edge of the trunk lid to apply film thereto in
the manner previously described. Since the roof panel will
typically be wider than the hood or trunk panels, it may be
preferred to use a second apparatus in tandem with the first
to apply film to the roof from wider supply rolls.
Figure 3 illustrates secondary applicator rolls 34 located
downstream of the primary rolls to smooth film onto profiled
panels. In the example shown, the rolls 34 are foam rubber
idler rolls suspended between inner struts 36 and outer
telescopic struts 38 from a cross-rail 40 so that they can
accommodate the profile of the panel. The number of rollers
and their lateral position and inclination can be varied to
suit the profile of the panel to be protected.
Referring to Figures 4-8, the apparatus shown in these
figures allow the apparatus to operate without downtime to
change film supply rolls. A roll holder 42 comprises spaced
triangular plates connected by a centre axle, with
pneumatical operated pintles 44 at each corner of each plate
to engage the cores of rolls 46 of film. Rolls of film are
placed on a stepper table 48 along which they can be advanced
to the right by a motor driven belt. During initial loading,
a first roll is advanced between and engaged by the pintles
44 of the lowermost apex of the roll holder (Figure 5) which
is then rotated to the position shown in Figure 6, so that a
second roll can be advanced between the pintles of a
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CA 02267813 1999-04-O1
following apex, and the prepared end of the first roll drawn
off manually and fed between the drive rolls 18. When the
first roll is almost exhausted, the holder 42 is again
rotated through 120° so that the tack side of the film is
wrapped around the second roll. In the meanwhile a third
roll is moved between and engaged by the pintles at the third
apex of the holder (see Figure 7) . A knife 50 then severs
the film from the first roll, and the pintles holding that
roll release its core which is conducted away to the right
hand end of the conveyor by a chute 52. The core can then be
removed and replaced by a fresh roll.
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