U.S. patent number 3,782,560 [Application Number 05/200,301] was granted by the patent office on 1974-01-01 for labelling machine with pneumatic monitor.
This patent grant is currently assigned to Eastman Kodak Company. Invention is credited to Ghassan N. Kahwati, Allen C. Mercer.
United States Patent |
3,782,560 |
Kahwati , et al. |
January 1, 1974 |
LABELLING MACHINE WITH PNEUMATIC MONITOR
Abstract
A high speed labelling machine which picks up and lays down
labels by means of an "apertured" pressure-and-vacuum head includes
a monitoring system for assuring against faulty labelling. The
monitoring system employs a pressure switch -- rather than a vacuum
switch -- to check for vacuum during the monitoring operation. Use
of a pressure switch as a vacuum detector is made possible by means
of a chamber connected to the head, and to which an auxiliary
internal pressure is applied ... the pressure switch being also
connected to the chamber.
Inventors: |
Kahwati; Ghassan N. (Rochester,
NY), Mercer; Allen C. (Brockport, NY) |
Assignee: |
Eastman Kodak Company
(Rochester, NY)
|
Family
ID: |
22741134 |
Appl.
No.: |
05/200,301 |
Filed: |
November 19, 1971 |
Current U.S.
Class: |
414/618;
294/186 |
Current CPC
Class: |
B65C
9/40 (20130101) |
Current International
Class: |
B65C
9/00 (20060101); B65C 9/40 (20060101); B66c
001/02 () |
Field of
Search: |
;294/64R,65
;214/1B,1BS,1BT,1BH,1BV |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Forlenza; Gerald M.
Assistant Examiner: Abraham; George F.
Attorney, Agent or Firm: W. T. French et al.
Claims
We claim:
1. An apparatus for handling label-like elements, comprising:
a hollow applicator head having at least one external aperture into
the hollow thereof,
means for selectively applying vacuum and pressure to said
head,
means for positioning an element to be handled so that it covers
said aperture, whereby the element may be picked up and laid down
by said head,
a pressurized chamber pneumatically connected continuously to said
head through an orifice of selected size, and
a pressure switch pneumatically connected to said chamber for
indicating pressure changes in said chamber resulting from applying
said vacuum to said head.
2. The apparatus of claim 1 further comprising means responsive to
a position of said pressure switch for generating a signal
indicating a malfunction of said apparatus.
3. The apparatus of claim 2 further comprising means responsive to
said signal for interrupting the operation of said apparatus.
4. The apparatus of claim 1 further comprising means for
maintaining the pressure of said chamber within selected
limits,
wherein the size of said orifice is such that said pressure in said
chamber decreases to a level sufficient to operate said pressure
switch only when the said element completely covers said aperture
or apertures in said applicator head.
Description
BACKGROUND OF THE INVENTION
Machines which are used to apply labels or the like to packages or
cartons are often used in high speed operations having a high
volume of production. These machines often have a movable
applicator head which picks up, prepares, then applies a label to a
carton or package. One way to pick up a label and hold it is by
means of a hollow "apertured" applicator head to which a vacuum is
applied. As a label is moved beneath the head, suction from the
vacuum causes the label to be drawn up against the head, covering
the apertures. This blocking of incoming air allows a partial
vacuum to be achieved in the applicator head. The label may then be
moistened or heated while the head is moved into a position for
application of the captive label to a package. When the head and
label are in contact with the package, the vacuum is turned off
and, simultaneously, a high pressure is introduced into the head,
and the label is blown firmly against the package.
In order to maintain realistic quality control levels and to
prevent a large number of rejects, the performance of the aforesaid
machine must be continuously monitored. Because machines of this
type operate at high speeds and have a large volume of production,
monitoring of the label application operation must occur almost at
the instant a label is applied to a package. If the monitoring
apparatus were employed later, by the time a malfunction was
detected and an alarm activated, too great a number of defectively
labelled packages would have been produced.
A method of detecting the presence of a label in position on the
applicator head is by sensing whether a vacuum has been achieved
inside the head. This is most easily done by connecting a vacuum
sensing switch to either the head or to the conduit connecting the
head and the pressure sources.
Vacuum sensing switches are theoretically ideal for this
application, but in practice their use has often presented
problems. One such problem is the high degree of sensitivity that
is necessary to detect a slight drop in pressure. A label in the
correct position on the head will cause only a slight drop from the
low pressure created by the suction when no label is on the head.
Such sensitivity problems are further compounded when a label being
held by a head is slightly askew, so that not all the suction holes
are covered, thus causing an even smaller decrease in pressure to
be detected. Vacuum sensors which can detect small changes in
pressure are notoriously difficult to calibrate and adjust, and
tend to be rather costly.
The type of machine on which such vacuum sensors are desired to be
used also presents a problem: in the normal course of production,
these machines may be required to use labels having different sizes
and shapes without changing the applicator head; such different
labels will present not only different, but also smaller, pressure
increments that must be detected. Detection of such small and
varied increments requires either substitution of a different
vacuum sensor or the recalibration of the existing one. Both of the
above solutions require the machine to be shut down for a period,
causing a loss of production which is highly undesirable.
Another problem stemming from the use of vacuum sensing switches is
their relatively slow response time; that is, the total time it
takes to sense a variation in pressure plus the time it takes for
the switch to change states.
As already mentioned, machinery of this type operates at high
speeds and can be made to operate so fast that the slow response
time of the vacuum switch is the limiting factor which prevents
further increases in operating speed.
These problems associated with vacuum switches have been tolerated
in the past as inherent system limitations. However, the search for
a more reliable, faster operating vacuum switch has been an ongoing
project.
SUMMARY OF THE INVENTION
To eliminate the aforesaid problems that have become associated
with vacuum sensing switches, the invention proposes the use of a
common pressure-sensing switch in combination with an external air
pressure supply and a specially designed pressure chamber, thereby
to remove the troublesome vacuum switch from the system.
Were a pressure-sensing switch to be used as a direct substitution
for a vacuum switch, it would serve only to indicate an increase in
air pressure. However, in a labelling machine of the indicated
type, the absence of high pressure does not indicate the presence
of a vacuum (i.e., a label in position) ... hence, such direct
substitution will not supply all the desired information in regard
to system performance.
The use of pressure sensing switches immediately overcomes one of
the drawbacks associated with vacuum switches: i.e., response time.
Pressure switches normally have a much faster response time than
vacuum switches. One reason for this is that a measureable change
in a relatively high pressure represents, for example, at least one
pound per square inch, while a measureable change in a relatively
low pressure (vacuum) represents a change of less than one-half
pound per square inch. More force on the diaphragm of a pressure
sensing device will allow the diaphragm to have greater travel and
will permit faster switch actuation.
Use of the invention also eliminates difficulties caused by
different size labels. The external air supply to the pressure
chamber is adjustable, and since such air supply controls the level
at which the pressure switch changes state, i.e., goes from on to
off, the system of the invention can easily be made to recognize
pressure changes caused by any size label. Such adjustments may be
made almost instantly by setting the external pressure to a
predetermined level, thereby obviating the necessity for any
machine shutdown.
The specially shaped chamber is provided with a small orifice at
the connection with the conduit leading to the applicator head,
thus effectively isolating the sensing apparatus from the main
system and preventing such apparatus from loading the system.
By allowing the external air pressure to remain on always to
pressure the chamber, the pressure switch tends to be actuated at
all times, air passing out of the chamber being expelled from the
applicator head apertures. Because of the small orifice at the
point where the chamber joins the indicated conduit, when the high
pressure air is applied to the head, most of it will not enter the
chamber but will be expelled from the applicator head. When the
vacuum is applied, air is both drawn in through the holes in the
applicator head and removed from the chamber through the
small-sized orifice. By providing the correct size for such
orifice, and by adjusting the external air pressure being fed into
the chamber, the pressure switch can be made to change states only
when the vacuum is on and a label is affixed over the apertures in
the applicator head. Another orifice is also provided in the
chamber to act as a pressure relief, since the chamber is
alternately pressurized and evacuated. Means are also providing for
producing an alarm signal and/or stopping the machine when a
nonconformance condition is detected, e.g., when a label is stuck
to the head when it should have been applied to a package.
To illustrate the advantages of the invention, it is shown and
discussed as means for improving an existing machine, but it should
be understood that the invention is not limited to this type of
application. The invention provides apparatus whereby a sensitive
pressure switch is adapted to perform, with greater sensitivity
than the function of a vacuum switch.
The invention will be described with reference to the figures,
wherein:
FIG. 1 is a schematic block diagram illustrating apparatus
embodying the invention, and
FIG. 2 illustrates waveforms useful in describing the
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, a web of material 21 having labels printed
thereon is caused to move by means of a drive roller 22; as the web
moves, a photoelectric cell 23 senses the discrete labels of the
web. The output signal from the photoelectric cell is used to
synchronize the cutting of the web 21 into detached labels, such
cutting being accomplished by a chopper 25. After being separated
from the web 21, an individual label 24 may be moved to the
position of an applicator head 26 by any suitable means such as
rollers or the like.
It should be noted that means for providing the correct sequence of
machine operations is shown as a controller 27; and such controller
may be in the form of a common timing sequencer consisting of
rotating cams and switches, or it might be an electronic timer with
no moving parts.
Since an objective of the invention is to detect the presence of a
label on the applicator head 26 at the earliest possible time, when
the machine is first started, an adjustable air pressure supply 30
connected to a chamber 31 is turned ON. The chamber 31 is connected
to a standard pressure sensitive switch assembly 32 having a
displaceable diaphragm 33 which operates a switch 34. Such switch
34 is electrically connected to logic 35 for indicating the state
of the switch assembly 32 The logic 35, depending on the operation
of the switch 34, operates an alarm 36 and a "machine stop" command
signal line 37. The chamber 31 is connected via a suitably small
orifice 42 to a main conduit 38 which runs to the applicator head
26. The adjustable air pressure 30, when ON, causes the pressure
inside the chamber 31 to be sufficiently high to cause the
diaphragm 33 to displace and place the arm of the switch 34 in
contact with a contact 1. This may or may not indicate a
malfunction, depending on the state of the alarm logic 35 and the
controller 27.
As the cut label 24 moves into position with respect to the
applicator head 26, a suction is applied to the head through the
main conduit 38 by actuation of a solenoid valve 28 which is
connected between the main conduit 38 and a vacuum source 40. Upon
applying the vacuum, air is sucked in through holes 41 in the
applicator head 26; and the pressure inside the main conduit 38 is
lowered. The chamber 31 also tends to be evacuated, causing its
pressure to be lowered accordingly. Because of the size of the
orifice 42 and the amount of air being supplied by the adjustable
pressure supply 30, the low pressure caused by the vacuum source 40
is not sufficient to overcome the higher pressure being supplied to
the chamber. This is a key feature of the invention. After the
label 24 has moved into position, the holes 41 in the applicator
head will be covered and the pressure inside the head 26 and the
main conduit 38 will drop even lower; and as this pressure drops,
it tends to overcome the high pressure in the chamber 31, creating
a partial vacuum and causing the diaphragm 33 to relax, thereby
placing the arm of the switch 34 in contact with a contact 2. This
indicates the presence of a relative vacuum at the head 26 and
hence the presence of a label. If a sequencing controller 27 has
signalled the alarm logic 35 that a label is required to be on the
head at this time (Test 1), then the switch 34 is in its correct
state and no malfunction condition will be indicated. If a label is
not in the required position, the suction created by vacuum source
40 will not be sufficient to overcome the pressure in the chamber
31; the diaphragm 33 will not relax; and the switch 34 will not be
in the correct state, when compared with the signal from the alarm
logic 35. This will indicate a malfunction and the machine will be
commanded to stop.
The operation thus having passed its first test successfully, i.e.,
a label 24 is present at the correct point in the cycle, the label
24 is heated to allow it to adhere to a carton or package 45 which
is being positioned for labelling by a conveyor belt 50. Label
heating is accomplished by heater wires 44 located inside the
applicator head 26, the temperature being controlled by a suitable
heater control 43. As the label is being heated, the applicator
head 26 is lowered towards the package 45 by suitable means 52. At
the instant that the applicator head 26 contacts the package, the
vacuum holding the label to the head is removed by closing the
solenoid valve 28 and, at substantially the same time, applying a
high pressure to the applicator head by turning (opening) a
solenoid valve 29. The solenoid valve 29 is connected by a suitable
conduit between a high pressure air supply 60 and the main conduit
38.
When high pressure air is applied to the head 26, the label 24 is
forced away from the head and into contact with the package 45, to
which it becomes firmly affixed, by the high pressure air being
expelled from the holes 41 in the applicator head. The high
pressure is then removed from the head 26 by closing the solenoid
valve 29, and suction is then applied again to the applicator head
by opening the solenoid valve 28. A signal from the sequence
controller 27 to the applicator head actuator 52 causes it to begin
to reposition the head 26 to receive the next label from the
chopper 25.
Since an objective of the invention is to prevent the production of
packages without labels, the applicator is checked (Test 2) to
determine that the label 24 is, in fact, gone, i.e., applied to a
package 45: Suction having been applied to the head 26, air enters
the holes 41 and causes the pressure in the main conduit 38 to
drop, but not sufficiently to overcome the relatively high pressure
in the chamber 31 caused by the pressure supply 30. The pressure in
the chamber 31 causes the diaphragm 33 to be displaced, and causes
the arm of the switch 34 to come into contact with the contact 1,
thereby indicating at this time, per the alarm logic 35, the
correct state for the head 26, i.e., no label present. Were a label
to be stuck on the applicator head 26, however, a vacuum would
exist sufficient to cause the pressure in the chamber 31 to be
overcome and to cause the arm of the switch 34 to be in contact
with contact 2, whereby the alarm logic 35 would cause a
malfunction to be indicated and the machine stopped.
In regard to FIG. 2, the relative states of the two solenoids 28
and 29 are shown in chart A as they are energized and de-energized
through one cycle of the labelling machine. At the point indicated
where neither solenoid is energized, a label is being positioned
beneath the holes in the applicator head 26. The vacuum is then
turned ON and the label is captured by the head. When the label is
seized by the applicator head, the head is caused to move downward
toward the package to be labelled, as indicated by waveform B, FIG.
2. At this time it is desired to test for the presence of a label
(Test 1).
Test 1 having been successfully passed, the label is applied to the
package by turning OFF the vacuum and turning ON the pressure as
shown by waveform A of FIG. 2. After the label is applied to the
package, the head is returned upward to its up position. At this
time, the head is checked (Test 2) to determine if the label has
indeed been applied.
If the label has been applied, the vacuum (applied during Test 2)
in the line 38 is insufficient to overcome the pressure of the
supply 30, causing operation of the alarm 36 as described above.
But assuming that Test 2 is completed without alarm, the vacuum is
turned OFF, and the next label moved into position beneath the
applicator head; the vacuum being thereafter again applied, causing
the pressure-vacuum cycle to begin anew.
The invention has been described in detail with particular
reference to preferred embodiments thereof, but it will be
understood that variations and modifications can be effected within
the spirit and scope of the invention.
* * * * *