The invention relates to an apparatus for applying gummed
paper tape to a box to be closed, containing:
- a supporting unit for carrying a roll of gummed
paper tape,
- a transporting and guiding unit for intermittently
transporting and guiding the gummed paper tape along a
path from the supporting unit to the box,
- a cutting unit for cutting the gummed paper tape
into strips,
- a moistening unit for moistening the gummed paper
tape, and
- an applying unit for applying the gummed paper tape
to the box to be closed after the gummed paper tape has
been moistened.
Suchlike apparatusses are used for manually, half-automatically
and fully-automatically applying gummed paper tape
to a box to be closed. The moistening unit for moistening
the layer of adhesive applied to the gummed paper tape
contains a brush, which is brought into contact with a
moistening agent, such as water. The disadvantage of known
apparatusses is that after a relatively short period of
use, however, the moistening unit does not work well
because the brush is not sufficiently saturated with
moistening agent. As a result the gummed paper tape does
not adhere adequately to the box. In order to remedy this
problem, the apparatus has to be stopped and the defect
put right. In addition, the use of gummed paper tape for
closing a box has the disadvantage that gummed paper tape
starts curling up in an uncontrolled manner after moistening
the adhesive layer applied to that, so that applying
gummed paper tape to the box takes place in a non-reproducible
way.
Among other things it is an object of the present invention
to provide an apparatus for applying gummed paper tape
to a box to be closed, in which the apparatus has a better
moistening unit with regard to the known apparatusses and
the gummed paper tape can be applied in a reproducible
manner to the box.
For this purpose a moistening unit as set out above is
characterized according to the invention in that
- two rolls placed on both sides of the path of the
gummed paper tape, in which the rolls can be being pressed
against each other with a specified pressure force,
- a holder for containing a moistening agent up to a
specified height, in which one of the rolls is rotatable
in the holder and is positioned for contacting the moistening
agent for moistening the gummed paper tape. Because
the moistening of the gummed paper tape is carried out by
a roll, the moistening of the gummed paper tape not only
appears to be very uniform, which improves the adherence
of the gummed paper tape to the box to be closed, but it
is also shown that a very large length of gummed paper
tape can be moistened without the degree of moistening
changing.
Preferably the moistening unit contains a control device
for keeping the height of the moistening agent constant.
It is thus ensured that for each amount of moistening the
holder contains in all cases exactly enough moistening
agent, such as water, for moistening the gummed paper
tape.
A preferred embodiment of the apparatus according to the
invention is characterized in that the moistening unit
contains a heating device for keeping the moistening agent
at a constant temperature. Because the degree of adherence
of the gummed paper tape on the box to be closed depends
on the temperature, an ideal adherence can be obtained
through the heating device.
In order to transport the gummed paper tape properly
through the moistening unit, an even moistening, among
other things, being obtained, one of the rolls is preferably
driven. Preferably the driven roll is the roll which
is rotatable in the holder.
If the pressure force is adjustable, then for each type of
gummed paper tape, for example of variable thickness or
weight of the gummed paper tape, an optimal moistening can
be fixed.
In an embodiment of an apparatus according to the invention,
the roll which is rotatable in the holder is a hard
roll, preferably made of aluminium, and provided with
circumferential grooves. The circumferential grooves serve
to receive the moistening agent from the holder and to
deliver it to the gummed paper tape.
In an alternative embodiment of the apparatus according to
the invention the roll which is rotatable in the holder
comprises a foam rubber roll.
Proper transport of the gummed paper tape through the
moistening unit is guaranteed, irrespective of the type of
foam rubber, if the roll placed in the holder comprises
two foam rubber rolls with a synthetic or rubber ring
placed therebetween.
With regard to foil tape gummed paper tape has the disadvantage
that when the gummed paper tape has been wound off
a supply roll, the rolled-off gummed paper tape starts to
curl up. When the gummed paper tape has been moistened,
the degree of curling up increases. Conversely gummed
paper tape is much cheaper than foil tape and the degree
of adherence to a box to be closed, made, for example of
recycled cardboard, is also several times higher.
In addition the invention provides an apparatus through
which the gummed paper tape can be transported without it
curling up, which contributes to an undisturbed functioning
of the apparatus.
For all kinds of the moistened gummed paper tape the
holder is preferably provided with a scraper in order to
prevent curling up of the moistened gummed paper tape
around the rotatable roll in the holder.
A further prefered embodiment of the apparatus according
to the invention is characterized in that the transporting
and guiding unit is provided with:
- a pair of guiding jaws, in which the guiding jaws
are placed on both sides of the path of gummed paper paper
tape, in which each guiding jaw is provided with a recess,
- a first pair of rolls, in which the rolls are
placed on both sides of the path of gummed paper tape, in
which the first pair of rolls is placed between the supporting
unit and the cutting unit, in which each roll
extends through the recess of the corresponding guiding
jaw, and in which the rolls of the first pair can be
pressed against each other with a specified pressure
force,
- a second pair of rolls, in which the rolls of the
second pair are placed on both sides of the path of gummed
paper tapepaper tape, in which the second pair of rolls is
placed between the cutting unit and the applying unit, and
in which the rolls of the second pair can be pressed
against each other with a specified pressure force,
- in which one roll of the first pair and one roll of
the second pair is driven. Because of this each type of
gummed paper tape is transported in a flat manner, that is
without curling up, along the cutting unit to the moistening
unit and the applying unit, the risk of undesirable
tearing of the gummed paper tape, particularly in the case
of lighter gummed paper tape, being negligible. As a
consequence the cutting also takes place reproducibly.
Preferably the second pair of rolls of the transporting
and guiding unit is formed by the pair of rolls of the
moistening unit, so that less parts are needed.
Preferably the roll of the first pair and the roll of the
second pair are jointly driven.
In order to keep the gummed paper tape taut whilst the
gummed paper tape is being cut, so that cutting is facilitated,
the diameter of the driven roll of the second pair
is larger than the diameter of the driven roll of the
first pair. For all types of gummed paper tape and roll
diameters, keeping the gummed paper tape taut appears to
be satisfactory, if the diameter of the driven roll of the
second pair is 1.5 mm larger than the diameter of the
driven roll of the first pair.
So as to apply the moistened gummed paper tape with the
proper adhesion to the box to be closed, the applying unit
comprises a smooth roll, which is preferably rotatable in
one direction only, so as to apply the gummed paper tape
to a defined place on the box to be closed.
By way of example some prefered embodiments of an apparatus
for applying gummed paper tape to a box to be closed
will be described on the basis of the drawing.
Figure 1 schematically shows a side view of an apparatus
according to the invention, figure 2 schematically shows a front view of the apparatus
according to figure 1, figure 3 schematically shows a more detailed view in cross
section of the inventive units of the apparatus according
to the invention for closing a box at the top, and figure 4 schematically shows a more detailed view in cross
section of the inventive units of the apparatus according
to the invention for closing a box at the bottom.
Figure 1 schematically shows a side view and figure 2
schematically shows a front view of an apparatus for
applying gummed paper tape to a box 5 to be closed. In the
example shown the apparatus is mounted to a fixed frame 1,
although it is clear that the apparatus can also be movably
mounted.
A transport means 2 for transporting the box 5 to be
closed through the apparatus is mounted to the frame. In
the example shown the transport means 2 is a roll conveyor,
although one or more conveyor belts or wire mesh
conveyors can be used. In order to centre the box 5 to be
closed well, thus guaranteeing the reproducible action of
the apparatus, the box 5 is confined in a lateral direction
by two side guiding conveyors 3. These side guiding
conveyors can each contain a conveyor belt, which can be
compressed in a lateral direction by the box 5 so as to
obtain good centering and good transport. Particularly in
the case of high boxes it is preferable if additional side
guides 4, for example in the shape of rolls, are used. The
distance between the side guiding conveyors 3 is adjustable
so as to receive boxes of different widths. The distance
is adjustable between 120 and 600 mm, for instance.
The apparatus contains a supporting unit 6 for supporting
a roll of gummed paper tape 7. The gummed paper tape 7 can
be of a variety of gummed paper tape types, and has a
width of 48 - 80 mm, for example, a weight of approximately
60 - 100 g/m2, and the weight can be even lesser or
greater. In addition, the apparatus contains a housing 9
in which a transporting and guiding unit, a cutting unit,
a moistening unit and an applying unit are accomodated.
The supporting unit 6 and the housing 9 are movably attached
in height with regard to the transport means 2 to a
bar 8 mounted to the frame 1. The height is adjustable
between 140 - 550 mm, for example.
The supporting unit 6 and the housing 9 are used for
closing the box 5 at the top. To be able to close a box at
the bottom, on the lower side of the transport means 2, an
additional housing 9' and an additional supporting unit 6'
for a roll of gummed paper tape 7' can be mounted to the
frame. The inventive units of the apparatus according to
the invention will henceforth be described on the basis of
units for closing the top of a box 5. The units for closing
the bottom of a box are analogous hereto, as can be
seen in figure 4, and only the differences from the units
for top closure of the box 5 will be discussed, where
necessary.
A box 5 to be closed can be moved continuously through the
apparatus, in which the box 5, passing a particular place,
and being detected, for instance, by a photo sensor,
activates the action of the units for applying the gummed
paper tape 7 to the box 5, such that there is a flap of a
specified length between the applying unit and the box at
the moment a box reaches the applying unit. Conversely the
transport of the box 5 on the transport means 2 can be
interrupted for a short while, so that gummed paper tape 7
has enough time to adhere well to the material of the box
7. After having passed through the apparatus, the box 10
will be closed at the top as well as at the bottom by a
strip of gummed paper tape 11 and 12, respectively.
In figure 3 the inventive units of an apparatus according
to the invention are schematically shown in cross section.
The supporting unit 6 is provided with a shaft on which a
roll of gummed paper tape 7 is arranged and is mounted in
its entirety to a bar 31. Via a guiding roll 14, which is
mounted to a swivelling arm 32 and via fixed guiding rolls
15 and 16 the gummed paper tape 7, unwound from the roll,
is brought into an almost vertical path which eventually
ends at the front of the box 5. A brake band 13 is attached
on the one hand to a fixed point 33 and on the other
hand to the swivelling arm 32, and surrounds the shaft of
the supporting unit 6. If a transport unit to be described
below draws off gummed paper tape from the roll, on account
of the tension in the gummed paper tape 7 the swivelling
arm 32 is lifted up and the shaft of the supporting
unit 6 and with it the gummed paper tape can rotate
freely. When the transport unit becomes inactive, the
swivelling arm 32 then descends and consequently presses
the brake band 13 against the shaft of the supporting unit
6, as a result of which the latter stops so that the
gummed paper tape 7 is kept taut.
When the path 30 of gummed paper tape 7 is branched off in
a vertical direction after the roll 16, the gummed paper
tape 7 comes in between a pair of guiding jaws 17 and 17',
which ensures a flat, that is a non-curling guidance of
the gummed paper tape 7. Each guiding jaw 17, 17' is
provided with one or more recesses 19, 19'. A first pair
of rolls 18, 18' is placed on both sides of the path 30 of
the gummed paper tape, each roll 18, 18' projecting
through the recess 19, 19' of the corresponding guiding
jaw 17, 17' to the gummed paper tape 7. The rolls 18, 18'
can be pressed against each other with a specified pressure
force, in order to transport the gummed paper tape 7
properly. Preferably the pressure force is adjustable, so
as to set the right pressure force for every type of
gummed paper tape. The adjustability of the pressure force
is schematically shown in figure 3 by an adjustable,
spring-loaded suspension 28 of the roll 18 in the housing
9.
Each roll of the first pair comprises at least two adjacently
placed smooth synthetic or rubber rolls, which are
spaced from each other, each smooth roll projecting
through its own recess in the corresponding guiding jaw.
Yet another part of the guiding jaw is present between
each recess, so that wide gummed paper tape can also be
transported by the guiding jaws 17, 17' without curling
up.
One of the rolls of the first pair, for example roll 18,
is intermittently driven by a drive, for example a pneumatic
motor 21.
The guiding jaws 17, 17' project downwards over an adequate
length, so as to guide the gummed paper tape 7 properly
to a cutting unit 20, 20'. The cutting unit comprises a
fixed knife blade 20' and a movable knife blade 20, which
are located on both sides of the path 30 of the gummed
paper tape 7.
There is a moistening unit for moistening the adhesive or
gum layer of the gummed paper tape 7 underneath the cutting
unit. The moistening unit is provided with two rolls
24, 26 placed on both sides of the path 30 of the gummed
paper tape 7, and the rolls 24, 26 can be pressed together
with a specified pressure force. The moistening unit is
morever provided with a holder 23 for containing a moistening
agent 25, such as water, to a specified height, for
instance. One of the rolls, roll 24 in the example given
in figure 3, is rotatably mounted in the holder 23 and is
in contact with the moistening agent 25 as well as with
the gummed paper tape 7, for moistening the gummed paper
tape. Because the moistening is carried out by a roll,
moistening the gummed paper tape not only appears to be
very uniform, but a very large length of more than 2 km
gummed paper tape can be moistened without the degree of
moistening changing, too.
Depending on the type of gummed paper tape, which thickness
or weight this has, for instance, a specified pressure
force can produce an ideal moistening. In order to
provide, in a simple way, an ideal moistening for each
type of gummed paper tape, the pressure force between the
rolls of the moistening unit is preferably adjustable.
This is schematically shown in figure 3 in that roll 26 is
adjustably mounted in a spring-loaded fashion 27 to the
housing 9.
The moistening unit further contains a control device for
keeping the height of the moistening agent 25 in the
holder 23 constant, so that there is always enough agent
25 at hand to guarantee a proper moistening, without the
holder having to be exceptionally large.
Since the degree of adhesion of the gummed paper tape 7 to
a box to be closed is in part dependent on the temperature,
the moistening unit is provided with a heating device
for keeping the moistening agent 25 at a constant temperature.
Hence the temperature of the agent 25 is almost
insensitive to varying ambient conditions, as a result of
which a reproducible adhesion of the gummed paper tape 7
to the box to be closed can be obtained.
The transport of the gummed paper tape through the moistening
unit takes place properly in all cases, for instance
without the gummed paper tape tearing if one of the rolls
24, 26 is driven, preferably the roll 26 which is rotatable
in the holder 23. For this drive advantageous use can
be made of the drive 21 of the driven roll of the first
pair of the transporting and guiding unit. In this case
the moistening unit in fact forms a part of the transporting
and guiding unit.
In an alternative embodiment the transporting and guiding
unit contains a second pair of rolls placed under the
cutting unit 20, 20' and on both sides of the path 30 of
the gummed paper tape. One of the rolls of the second pair
is then intermittently driven by a drive, for example a
pneumatic motor. Preferably the driven rolls are driven
jointly by one motor 21 in order to obtain a highly synchronized
transport.
In order to prevent the gummed paper tape 7 from slackening
because of turning back the rolls when the drive is
at a standstill, the driven rolls are preferably rotatable
in one direction only.
When the gummed paper tape 7 comes in between the pair of
rolls 24, 26 for the first time, a certain blockage of the
gummed paper tape 7 can occur, whereby the gummed paper
tape is somewhat deformed. In order to overcome this
deformation the diameter of the driven roll 26 is larger
than the diameter of the driven roll 18 of the first pair.
The gummed paper tape 7 is thus stretched taut, as a
result of which all deformations in the gummed paper tape
7 are removed. As an additional advantage the cutting of
the taut gummed paper tape 7 can take place more reproducibly.
It has been shown that for all types of gummed paper tape
deformations can be removed if the diameter of the driven
roll of the moistening unit is 1.5 mm larger than the
diameter of the driven roll of the first pair. As an
alternative the driven rolls of the first pair and the
moistening unit can have an equal diameter, the driven
roll of the moistening unit being driven at a higher
velocity than that of the first pair.
It has been shown in practice that for all types of gummed
paper tape a proper transport is realized if the roll of
the moistening unit, which is not rotatable in the holder,
contains a number of adjacently placed synthetic or rubber
rings.
A hard roll provided with circumferential grooves is
provided as a roll for moistening the gummed paper tape,
preferably a roll of stainless steel material, such as
aluminium, or a roll of foam rubber being extremely appropriate,
although other rolls can be used.
It has been shown that depending on the type of foam
rubber that is used for the roll, a foam rubber roll is
less suited for moistening the gummed paper tape which is
intended for closing the bottom of a box to be closed. On
account of the other rotational direction of this roll
this can lead to a certain blockage of the moistening
agent on the gummed paper tape, and the moistening is
therefore of lesser quality. This blockage can also be
considered a kind of chamois effect. For this reason it
could be preferable using a hard roll with circumferential
grooves for moistening gummed paper tape which is intended
for the bottom of a box to be closed.
If a foam rubber roll is used, then a proper transport of
the gummed paper tape through the moistening unit is
guaranteed, irrespective of the type of foam rubber, if
the roll placed in the holder comprises two foam rubber
rolls with a synthetic or rubber ring therebetween.
In order to prevent the moistened gummed paper tape 7 from
curling around the moistening roll 24, the holder is
provided with a scraper 34. For the moistening unit that
is intended for moistening the gummed paper tape for closing
the top of a box, the scraper is integrated in the
base of the holder 25, for instance. For the moistening
unit that is intended for moistening gummed paper tape for
bottom of a box, there is a scraper above the moistening
roll.
An applying unit is located underneath the moistening
unit, which comprises a smooth roll 29 rotatable preferably
in one direction only, which presses the gummed paper
tape 7 against a box 5 to be closed. The activation of the
apparatus, through a box passing a specified place, is
such that the intermittent drive draws off enough gummed
paper tape from the roll, that a flap with a specified
length is transported between the roll 29 and the box 5,
which flap is pressed against the box. The length of the
flap can be adjusted by the degree of intermittent drive.