LABELLING MACHINE WITH A LABELLING STATION HAVING A RESILIENT GLUING ROLLER

ETIQUETEUSE MECANIQUE A ROULE SOUPLE D'ENCOLLAGE

English Abstract

ABSTRACT
A labeling machine for objects such as bottles has a labeling
station with a glue roller (1) that has an elastic glue roller covering. A
glue scraper (4) defines with the glue roller surface a gap that is adjustable
in order to regulate the thickness of the glue coating. Adjustment of the
glue scraper (4) takes place as a function of the machine output in such a way
that at higher machine outputs the gap is reduced and at lower machine outputs
the gap is increased. This adjustment of the glue scraper (4) as a function
of the machine output compensates for the flattening of the glue roller (1)
that occurs as a result of the glue pressure.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A labeling machine for objects such as bottles, said machine
having a control system for the machine output and a labeling station that
applies glued labels to the objects, glue being applied to the surface of a
glue roller by a feed element, the surface portion of the glue roller being
elastically deformable, the application thickness of the glue on the roller
being adjustable by means of a glue scraper that defines a gap with the surface
of the glue roller, wherein the glue scraper is adjustable by means of an
adjusting element as a function of the machine output such that when the output
is increased the gap width becomes smaller and when the output is reduced
the gap width becomes greater so that the thickness of the glue coating on the
glue roller is substantially constant at each level of machine output.
2. A labeling station according to Claim 1, wherein the thickness
of the glue coating on the glue roller is measured by a sensor that is arranged
after the glue scraper in the direction of rotation of the glue roller, the
measured values so obtained being passed to a control system.
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Description

10~
This invention relates to a labcling machine for objects such as
bottles. The machine has a control system for the machine output and a label-
ing station that applies glued labels to the objects. The labeling station has
a glue roller which is resilient at least in the surface layer thereof and
upon the coating thickness of the glue applied by a feed element can be adjusted
by means of a scraper.
It is known that the thickness of the glue coating depends on the
temperature-dependent viscosity of the glue. Since the temperature of the
glue changes during the operating time, in order to keep the glue coating
thickness constant it is necessary to readjust the scraper so as to reduce the
application gap after the system has been in operation for a specific time.
However, it is impossible to maintain a constant thickness of the glue coating
during operation by this adjustment alone. It has been found that the thick-
ness of the glue coating varies with the power output of the machine and thus
with the rotational speed of the glue roller. It is desired to provide a
labeling machine in which variation in the thickness of the glue coating as
a function of machine output is avoided.
The invention provides a labeling machine for objects such as
bottles, said machine having a control system for the machine output and a
labeling station that applies glued labels to the objects, glue being applied
to the surface of a glue roller by a feed element, the surface portion of the
glue roller being elastically deformable, the application thickness of the
glue on the roller being adjustable by means of a glue scraper that defines a
gap with the surface of the glue roller, wherein the glue scraper is adjust-
able by means of an adjusting element as a function of the machine output such
that when the output is increased the gap widtll becomes smaller and when the
output is reduced the gap width becomes greater so that the thickness of the
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glue coating on the glue roller is substantially constant at each level of
machine output.
The present invention is based on the knowledge that at a higher
machine output (and corresponding higher speeds of rotation of the glue roller)
the glue that builds up on the glue scraper exerts a greater pressure on the
glue roller than is the case when machine output is lower. This increased
pressure leads to a greater flattening of the elastic glue roller cover and
thus to an increase in the glue roller gap. Such variation of the glue gap
as a function of power output is compensated for by adjustment of the glue
scraper.
The correct adjustment of the glue scraper as a function of
machine output can take place empirically. For example, the control system can
be suitably programmed. The correct adjustment of the width of the gap can be
monitored directly according to one configuration of the invention in that
the glue coating thickness on the roller cover is measured by means of a sensor
arranged after the glue scraper in the direction of rotation of the glue roller,
and the measured value so obtained passed through a control system. Insofar
as the adjustment that is made is not correct, a correcting adjustment is made
by means of the control system. In this case what is involved is a closed
feedback loop. This configuration of the invention is particularly advantage-
ous since it also makes allowance for changes in the glue coating thickness
that are brought about indirectly by changes in viscosity. Naturally, it is
also possible to measure the temperature of the glue directly, e.g., on the
glue scraper, and pass this value to the control system. In this case, the gap
width necessary for the desired thickness of the glue coating can be set without
the use of a sensor for the glue coated thickness, on the basis of empirical
values both as a function of the glue temperature and as a function of the

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machine output.
The present invention is described below, by way of example only
with reference to the accompanying drawings, wherein:
Figure 1 is a plan view, partially in section, showing a glue
roller with a glue scraper; and
Figures 2 and 3, show various positions of the glue scraper.
Glue is applied by a feed element 2 onto a rotating glue roller 1
in the upper area of the glue roller 1. This glue builds up on a glue scraper
4 that has a hollow throat 3. The scraper edge of the glue scraper 4 together
with the coating of the glue roller 1 forms an adjustable application gap 5.
Since the glue in the hollow throat 3 builds up as a rotating column that flows
downwards, a constant quantity of glue per unit of length flows through the
gap 5 across the whole length of the glue roller.
The glue scraper 4 has a plurality of channels 6 on its back,
extending throughout its length and through which a cooling medium can be sup-
plied in an upwards direction, i.e. counter to the direction of flow of the
glue roll. By controlling the supply of cooling medium it is possible to reduce
variations in the temperature of the glue that occur during operation.
The glue scraper 4 is supported by a guide sleeve 8 that carries
a pivotable shaft 9. A spring loaded ball detent 10 engages in a recess 11 on
the shaft 9 and thus determines the base position of the glue scraper 4. The
guide sleeve 8 can be pivoted on the rotating shaft 9 by means of an adjuster
motor 12 that is supported by the shaft 9 through an arm 13. In this manner
it is possible to adjust the scraper 4 angularly in the direction of the
arrows 14.
The adjuster motor 12 receives signals from the control system 15.
I`he control system 15 provides these adjusting signals according to a program

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that is provided for it as a function of output signals that are passed to it
from the machine. When the power output of the machine is increased the
guide sleeve 8 is adjusted clockwise so as to reduce the gap 5, whereas when
the power output of the machine drops this adjusting movement takes place in
the opposite direction. It is possible to ascertain whether or not the correct
gap width has been set by the control system 15, using a sensor 16 that mea-
sures the thickness of the glue coating. A correction is made if the actual
value of the glue coating thickness deviates from the desired value. In this
manner it is possible to take into account incorrect values brought about by
changes in viscosity.