U.S. patent application number 10/505671 was filed with the patent office on 2005-05-19 for method for controlling a blister packaging machine.
Invention is credited to Christ, Richard.
Application Number | 20050102977 10/505671 |
Document ID | / |
Family ID | 32667804 |
Filed Date | 2005-05-19 |
United States Patent
Application |
20050102977 |
Kind Code |
A1 |
Christ, Richard |
May 19, 2005 |
Method for controlling a blister packaging machine
Abstract
The invention concerns a method for controlling a blister
packaging machine having a work station which at least operates in
cycles and which performs at least one first adjusting motion for a
time period T.sub.V1 during one work cycle, followed by a treatment
state for a time period T.sub.B, in which a product and/or material
is treated. A second adjusting motion is then performed for a time
period T.sub.V2. A cycle rate R (=cycles/min) of the packaging
machine can be entered through an input means. The time periods
T.sub.V1, T.sub.B and T.sub.V2 can each be entered directly or
indirectly irrespective of each other via the input means. A
processing unit examines whether the entered time periods T.sub.V1,
T.sub.B, T.sub.V2 are within predetermined limits and whether their
sum is smaller or equal to a maximum cycle time T.sub.max.
Inventors: |
Christ, Richard;
(Emmelshausen, DE) |
Correspondence
Address: |
LICHTI LEMPERT & LASCH
BERGWALDSTR. 1
D- 76227
KARLSRUHE
DE
|
Family ID: |
32667804 |
Appl. No.: |
10/505671 |
Filed: |
August 25, 2004 |
PCT Filed: |
January 20, 2004 |
PCT NO: |
PCT/EP04/00379 |
Current U.S.
Class: |
53/453 ; 53/561;
53/64; 53/75 |
Current CPC
Class: |
B65B 9/045 20130101;
B65B 57/00 20130101; B65B 5/103 20130101; B65B 9/04 20130101 |
Class at
Publication: |
053/453 ;
053/064; 053/075; 053/561 |
International
Class: |
B65B 047/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 23, 2003 |
DE |
103 02 726.2 |
Claims
1-9. (canceled)
10. A method for controlling a blister packaging machine, the
machine having a work station which operates in cycles and which
performs at least one first adjusting motion within a time period
T.sub.V1, performs a subsequent treatment stage within a time
period T.sub.B in which a product and/or material is processed, and
then executes a second adjusting motion throughout a time period
T.sub.V2, the method comprising the steps of: a) entering a cycle
rate R of the packaging machine using an input means; b) entering
the time period T.sub.V1 via the input means; c) entering the time
period T.sub.B via the input means; d) entering the time period
T.sub.V2 via the input means; e) examining, using a processing
means, whether T.sub.V1, T.sub.B, and T.sub.V2 are each within a
respective predefined limit; and f) examining whether the sum of
T.sub.V1+T.sub.B+T.sub.V2 is less than or equal to a maximum cycle
time T.sub.max.
11. The method of claim 10, wherein the work station is a forming
station having forming plates which can be adjusted relative to
each other and between which a bottom sheet is provided with
cup-like receptacles.
12. The method of claim 11, wherein the first adjusting motion is a
closing motion of the forming plates, the bottom sheet being
provided with the cup-like depressions in the treatment stage,
wherein the second adjusting motion is an opening motion of the
forming plates.
13. The method of claim 10, wherein the work station is a sealing
station with sealing plates which can be adjusted relative to each
other and between which a cover sheet is sealed onto a bottom
sheet.
14. The method of claim 13, wherein the first adjusting motion is a
closing motion of the sealing plates, and the cover sheet is sealed
onto the bottom sheet during the treatment stage, with the second
adjusting motion being an opening motion of the sealing plates.
15. The method of claim 10, wherein a speed v.sub.S of the first
adjusting motion is limited to a maximum speed v.sub.smax and a
desired speed v.sub.sg of the first adjusting motion is entered as
a percentage (.ltoreq.100%) of the maximum speed v.sub.smax,
wherein the processing unit determines the time period
T.sub.v1=s.sub.v/v.sub.sg for a predetermined adjusting path
s.sub.v.
16. The method of claim 10, wherein a speed v.sub.0 of the second
adjusting motion is limited to a maximum speed v.sub.omax and a
desired speed v.sub.og of the second adjusting motion is entered as
percentage (.ltoreq.100%) of the maximum speed v.sub.omax, wherein
the processing unit determines the time period
T.sub.V2=s.sub.v/v.sub.og for a predetermined adjusting path
s.sub.v.
17. The method of claim 10, wherein the time period T.sub.B is
entered directly via the input means.
18. The method of claim 10, wherein the cycle rate R is entered
directly via the input means and the processing unit determines the
maximum cycle time, T.sub.max=1/R (min)=60,000/R [ms], therefrom.
Description
[0001] The invention concerns a method for controlling a blister
packaging machine having a work station which at least operates in
cycles and performs at least one first adjusting motion for a time
period T.sub.V1 during one work cycle, assumes a subsequent
treatment state for a time period T.sub.B, in which a product
and/or material is/are treated, and performs a second adjusting
motion for a time period T.sub.V2, wherein a cycle rate R
(=cycles/min) of the packaging machine can be entered by an input
means.
[0002] A blister packaging machine of conventional-structure
comprises a forming station, in which a plurality of cup-shaped
depressions are formed into a bottom sheet which consists of
plastic material or aluminium, into which a product, e.g. a
pharmaceutical tablet is inserted in a downstream filling station.
After product supply, the bottom sheet is supplied to a sealing
station. A cover sheet is fed directly before or within the sealing
station and disposed on the bottom sheet. The cover sheet is sealed
tightly onto the bottom sheet within the sealing station using heat
thereby enclosing the product in the cup-shaped depression.
[0003] The forming station is operated in cycles and therefore
discontinuously. The sealing station can also be operated in cycles
or, alternatively, continuously, wherein conventional compensation
means effect transfer between cyclical operation of the forming
station and continuous operation of the sealing station.
[0004] The efficiency of a blister packaging machine depends mainly
on the cycle rate R, i.e. the number of cycles per minute to be
effected. The cycle rate R defines the maximum cycle time T.sub.max
available for a working cycle in milliseconds with
T.sub.max=60,000/R ([ms], i.e. at a cycle rate R of 75 cycles/min,
the maximum cycle time T.sub.max=800 ms. A graph of a corresponding
working cycle is shown in FIG. 2a in the form of a simplified
polygonal path-time-diagram and is briefly explained below.
[0005] The cyclically operated forming station must e.g. carry out
various motions and treatments or processes within the maximum
cycle time T.sub.max. Departing from a basic or zero position at
the beginning of the cycle (point 0 in FIG. 2a), in which two
forming plates, between which the bottom sheet to be formed
extends, are completely separated, a first adjusting motion, i.e.
the closing motion of the forming plates is initially carried out.
The closing path sv is defined by the technical production
requirements and the closing motion is performed over a
predetermined time period T.sub.V1 until point 1 (FIG. 2a) is
reached, at which time the forming plates are closed and have
reached their final position.
[0006] The forming plates have now reached their treatment state in
which e.g. a pre-heated plastic bottom sheet is cooled for a time
period T.sub.B, wherein the cup-shaped depressions are additionally
formed in the bottom sheet, in particular through compressed air or
forming dies. At point 2 of the cycle curve, cooling or treatment
of the bottom sheet is completed and is followed by a second
adjusting motion, i.e. the opening motion of the forming plates,
which is effected again via path s.sub.V (however, in the opposite
direction) over a time period T.sub.V2. At the end of the opening
motion, i.e. at point 3 of the cycle curve, the initial position
has been reached again.
[0007] A very short, negligible opening time caused by computer or
software processing or a resting period may follow which will be
neglected herein. As soon as the forming plates are opened to a
sufficient degree, further transport of the bottom sheet can be
initiated and performed. With respect to FIG. 2a, it is assumed
that the further transport of the bottom sheet starts when the
forming plates have been moved apart by a distance s.sub.V/2, i.e.
a time period t.sub.Z1 is available for further transport of the
bottom sheet to the end of the cycle, and a time period t.sub.Z2
from the start of the subsequent cycle to the time when the forming
plates are half closed again, which produces a total transport time
T.sub.Z from the sum of t.sub.Z1 and t.sub.Z2.
[0008] In earlier blister packaging machines, the curve shapes were
mechanically determined by rotating cam plates whose rotary motion
was derived from a central driven main shaft, the so-called king
shaft. In modern blister packaging machines, the curves are stored
in software and the motor drive of the adjusting motions is
effected via servomotors which are controlled by control
electronics or corresponding software. The servo drive is
particularly advantageous if an additional stroke adjustment or
switching off is required during operation. These functions can be
realized and changed without additional mechanical effort.
[0009] The motion sections of the cycle curve of a blister
packaging machine are usually designed to optimally satisfy the
process requirements of the customer thereby providing maximum
cycle rates. Once set, this cycle curve is taken as a basis for
later processing of all products during operation of the blister
packaging machine.
[0010] In practice, the blister packaging machine often cannot be
operated at the maximum possible cycle rate of e.g. 75 cycles per
minute, since e.g. the warm bottom sheet is relatively sensitive to
tensile forces and the time T.sub.Z available for further transport
of the sheet (FIG. 2a) requires such a high sheet acceleration at
maximum drawn length that the sheet is deformed. Problems in other
stations of the blister packaging machine, e.g. in the filling
station, may necessitate reduction of the cycle rate.
[0011] If the cycle rate R is reduced to prevent sheet deformation,
the maximum cycle time T.sub.max is increased for each cycle. If
the cycle rate R is reduced to 50 cycles per minute, the maximum
cycle time is T.sub.max=60,000/50=1,200 (ms). In a conventional
blister packaging machine, the stored cycle curve is basically
maintained, however, all time periods T.sub.V1, T.sub.B and
T.sub.V2 are extended by a factor 1,200/800=1.5. This facilitates
controlled coordination of all motions which depend on the forming
plate motion, e.g. the forming die motion, the distorting motion or
the heating plate motion. FIG. 2b shows a corresponding expanded
cycle curve which shows that the transport time T.sub.Z for the
sheet which results from the sum of the extended time periods
t'.sub.Z1 and t'.sub.Z2 is also increased by 50% which provides
e.g. more time for sheet transport. However, extension of the
working cycle reduces the efficiency of the packaging machine from
75 cycles per minute to 50 cycles per minute, i.e. to
50/75=66.7%.
[0012] It is the underlying purpose of the invention to provide a
method for controlling a blister packaging machine which permits
the machine operator to variably adjust the cycle curve or the
motion curve to the production and working conditions of the
packaging machine.
[0013] This object is achieved in accordance with the invention
with a method having the characterizing features of claim 1. The
time period T.sub.V1, the time period T.sub.B and the time period
T.sub.V2 are each input directly or indirectly, independently of
each other via the input means, and a processing unit is provided
for examining whether the entered time periods T.sub.V1, T.sub.B
and T.sub.V2 are within predetermined limits and whether their sum
is smaller or equal to a maximum cycle time T.sub.max.
[0014] The invention is based on the fundamental idea of not only
compressing or expanding a predetermined curve shape in total but
to individually adjust the individual sections of the curve and
merely check whether the predetermined boundary conditions are met.
In this fashion, each curve section can be individually adjusted to
the respective production conditions to obtain a higher cycle rate
R and therefore a better efficiency of the packaging machine
compared to conventional compression or expansion of the overall
cycle curve.
[0015] The work station whose cycle curve can be varied, may be a
forming station of a blister packaging machine. The forming station
has two forming plates which can be adjusted relative to each other
and between which a bottom sheet having cup-shaped receptacles is
provided. If the bottom sheet is made from plastic material, it is
processed in a pre-heated state and cooled in the forming station.
The first adjustment motion is then provided through the closing
motion of the forming plates, wherein the closing motion is
terminated only when the final position of the forming plates has
been reached, and the forming plates may already abut in the last
motional phase of the closing motion. At the end of the closing
motion, the forming plates remain in a treatment state for a time
period T.sub.B, in which the bottom sheet is shaped and optionally
cooled. The second adjusting motion is the opening motion of the
forming plates which return into their initial open position.
[0016] Alternatively, the work station may be a sealing station
with sealing plates which can be adjusted relative to each other
and between which a cover sheet is sealed onto the bottom sheet. In
this case, the first adjusting motion is the closing motion of the
sealing plates which remain in a treatment state at the end of the
closing motion for a time period T.sub.B in which the cover sheet
is sealed onto the bottom sheet. The second adjusting motion is the
opening motion of the sealing plates.
[0017] Time values, in particular in ms, can be entered directly
for the independent input of the time periods T.sub.V1, T.sub.B and
T.sub.V2. In practice, indirect input of the mentioned time periods
has proven to be advantageous by entering a value for a desired
speed v.sub.sg of the first adjusting motion or the closing motion
and a value for a desired speed v.sub.og of the second adjusting
motion or opening motion. These values are preferably input not as
absolute values but as relative values. Towards this end, a speed
v.sub.s of the first adjusting motion is limited to a maximum speed
v.sub.smax and the desired average speed v.sub.sg of the first
adjusting motion is input as percentage (.ltoreq.100%) of the
maximum possible speed v.sub.smax from which the processing unit
determines the time period T.sub.V1=s.sub.v/v.sub.sg for a
predetermined adjustment path s.sub.v.
[0018] The speed v.sub.0 of the second adjusting motion is
correspondingly limited to a maximum speed v.sub.0max and the
desired average speed v.sub.og of the second adjusting motion is
input as percentage (.ltoreq.100%) of the maximum speed v.sub.0max
from which the processing unit determines the time period
T.sub.V2=s.sub.V/v.sub.og for a predetermined adjustment path.
[0019] The duration T.sub.B of the treatment state is preferably
directly input as an absolute value in ms via the input means.
[0020] The desired cycle rate R (=cycles per minute) is also
directly entered via the input means, wherein the processing unit
determines the maximum available cycle time T.sub.max=1/R
[min]=60,000/R [ms] from the input cycle rate R.
[0021] Further details and features of the invention can be
extracted from the following description of an embodiment with
reference to the enclosed drawing.
[0022] FIG. 1 shows a schematic illustration of the essential
components of a blister packaging machine;
[0023] FIG. 2a shows a simplified normal cycle curve as
path-time-diagram;
[0024] FIG. 2b shows the cycle curve stretched by the factor 1.5 in
accordance with FIG. 2a;
[0025] FIG. 3 shows the possible selections for the time period
T.sub.V1;
[0026] FIG. 4 shows the possible selections for the time period
T.sub.B;
[0027] FIG. 5 shows the possible selections for the time period
T.sub.V2;
[0028] FIG. 6 shows an inventive modified cycle curve; and
[0029] FIG. 7 shows a schematic plan view of an input means.
[0030] FIG. 1 schematically shows the essential components of a
blister packaging machine 10. A plastic bottom sheet 11 delivered
by a supply is initially supplied to a heating station 12 which
comprises a lower heating plate 12b and an upper heating plate 12a
which can be adjusted relative to the lower heating plate 12b. When
the two heating plates 12a and 12b are closed, the bottom sheet
received therebetween is heated.
[0031] A forming station 13 is directly adjacent to the heating
station 12 and comprises a lower forming plate 13a and an upper
forming plate 13b which can be adjusted relative thereto. The two
forming plates 13a and 13b, which are shown in the open position,
can be closed thereby cooling the bottom sheet which is received
between the closed forming plates 13a and 13b and at the same time
providing it with cup-shaped depressions via a compressed air
supply or forming dies. The forming station 13 is followed by a
transport device 14 for pulling the bottom sheet 11 in cycles
through the individual stations.
[0032] The bottom sheet 11 which is provided with the cup-like
depressions is supplied to a filing station 17 via deflecting
rollers 15 and 16, in which a product, e.g. a pharmaceutical
tablet, is inserted into each depression. The bottom sheet 11
extends to a sealing station 20. A cover sheet 18 is disposed onto
the bottom sheet 11 directly before the sealing station 20 via a
deflecting roller 19. The cover sheet 18 is sealed onto the bottom
sheet 11 in the sealing station 20, which comprises a lower sealing
plate 20b and an upper sealing plate 20a, by closing the warm
sealing plates 20a and 20b and under thermal action on the sheet.
The sealing station 20 is followed by a further transport device 21
whose motion is synchronized with the transport device 14 and
provides cyclic transport of the sheet compound provided after the
sealing station 20.
[0033] FIG. 2a shows the above-explained simplified
path-time-diagram of a cycle curve of e.g. the forming station 13.
The assumed maximum cycle time T.sub.max is 800 ms which
corresponds to a cycle rate R of 75 cycles per minute. The two
forming plates 13a and 13b start from an open basic position and
are closed within a time period T.sub.V1, thereby moving along the
closing path s.sub.V as predetermined by production considerations.
As soon as the forming plates 13a, 13b have reached the final
position of their closing motion (point 1 of the curve in FIG. 2a),
the treatment state starts which extends over a time period
T.sub.B. During the treatment state, the bottom sheet is provided
with cup-shaped depressions. If the bottom sheet is made from
plastic material, it is also cooled. The treatment state is
finished at point 2 of the curve and the forming plates 13a and 13b
are subsequently opened via path s.sub.V in an opposite direction
to the closing motion and over a time period T.sub.V2. The initial
position is reached again at the end of the opening motion at point
3 of the curve.
[0034] In FIG. 2a it was assumed that the further transport of the
sheet with half-opened forming plates 13 and 13b starts or ends to
obtain a total transport time T.sub.Z=t.sub.Z1+t.sub.Z2.
[0035] If the user notices that this total transport time T.sub.Z
is not sufficient, he/she can re-define the cycle curve. The user
will initially check whether he/she can reduce the duration T.sub.B
of the treatment state thereby maintaining the current cycle rate
R. Moreover, the closing speed v.sub.s may optionally be increased
which reduces the time period T.sub.V1. Additionally or
alternatively, the opening speed v.sub.0 may be increased which
reduces the time period T.sub.V2. If one of these changes is
possible without violating specifications determined by production
needs or machine constraints, the user gains time which he/she can
use to increase the total transport time T.sub.Z of the sheet.
[0036] If the time periods T.sub.V1, T.sub.B, T.sub.V2 cannot be
changed or only to an insufficient degree, the user will reduce the
cycle rate R. Towards this end, the user will set a reduced cycle
rate R (=cycles per minute) to determine the maximum available
cycle time T.sub.max=60,000/R [ms]. It is e.g. assumed that the
user reduces the cycle rate R to 60 cycles per minute which
corresponds to a modified maximum cycle time T.sub.max=1000 ms.
[0037] The user can then set another closing speed of the forming
plates 13a and 13b via the input means shown in FIG. 7. A maximum
speed v.sub.smax is predetermined for the closing motion which
corresponds to a minimum time period T.sub.V1min for a fixed
closing path s.sub.V. Moreover, a minimum value is given for the
closing speed which corresponds to a maximum time period
T.sub.v1max (FIG. 3). The user can select any value within these
limits.
[0038] The closing motion of the forming plates should preferably
be carried out as quickly as possible. If no problems occurred
during closing, the user can select the same closing speed as for
the originally predetermined cycle curve of FIG. 2a. The closing
speed is selected via the input means 30 of FIG. 7 as a percentage
of the maximum closing speed v.sub.smax, i.e. in the present
embodiment 100%.
[0039] The user can also change the opening motion of the forming
plates within predetermined limits in accordance with the closing
motion. These limits are determined by a predetermined maximum
opening speed v.sub.omax which corresponds for a predetermined
opening path s.sub.V to a minimum opening time T.sub.V2min and a
minimum opening speed v.sub.Omin which corresponds to a maximum
opening time T.sub.V2max. Between these two limits, the user can
select from a plurality of opening curves as indicated in FIG. 5.
The user enters the desired opening speed for the opening motion as
a percentage of the maximum opening speed v.sub.omax. It is assumed
that the maximum opening speed v.sub.omax is also selected in this
case which also corresponds to an input of "100%".
[0040] The user can also set the duration of the treatment state on
the input means 30 as an absolute value in ms, i.e. the time period
T.sub.B in which the two forming plates are closed and the sheet is
shaped (forming station) or sealed (sealing station). In accordance
with FIG. 4, he/she can select within predetermined limits, i.e.
between a minimum cooling time T.sub.Bmin and a maximum time
T.sub.Bmax. The user will select the duration of the treatment
state in correspondence with the material-specific characteristics
of the bottom sheet such that proper treatment of the bottom sheet,
e.g. cooling and shaping in the forming station 13, is reliably
ensured. In the embodiment shown, it is assumed that he/she will
use the duration of the treatment state from the original cycle
curve of FIG. 2a.
[0041] Since the user has selected the same motion curve as in the
initial situation of FIG. 2a, but has reduced the cycle rate to 60
cycles per minute thereby increasing the cycle time to 1,000 ms,
200 ms are still available within a working cycle when the opening
motion is terminated and the forming plates are re-opened. The user
can use these 200 ms for transport of the bottom sheet (FIG. 6) and
can also use at least part of the time gained to increase the
duration of the treatment state TB.
[0042] FIG. 6 shows that it is possible through the user-dependent
determination of the cycle curve within predetermined limits to
increase the time periods for the sheet transport and/or duration
of the treatment period without delaying the closing or opening
motions of the forming plates.
[0043] FIG. 7 shows that the input means 30 is associated with a
processing unit 40 which determines the corresponding cycle curves
from the input values and in particular examines whether the
entered values of the cycle curve are within the predetermined
limits and whether the cycle curve in total is smaller or equal to
the cycle time T.sub.max. The sum of the time periods T.sub.v1,
T.sub.B, T.sub.V2 is also confirmed to be smaller or equal to the
cycle time T.sub.max.
* * * * *