US007299604B2

(12) United States Patent (10) Patent No.: US 7,299,604 B2

(54) METHOD AND APPARATUS FOR MOVING A 4,825,625. A * 5/1989 Hufford ....................... 53,451
WELDING UAW 4,829,752 A * 5/1989 Focke et al. ............... 53 3719
5,063,727 A * 11/1991 Patelli ......................... 53/552
(75) Inventors: Roman Kammler, Worms (DE): 5,347,795 A * 9/1994 Fukuda ........................ 53/552
Walter Baur, Gruendau (DE) 5,540,802 A 7/1996 Totani ........................ 156,359
5,822,949 A * 10, 1998 Naoi ............................. 53/55
(73) Assignee: Rovema Verpackungsmaschinen 5,860,270 A * 1/1999 Gerwe .............. ... 53,477
GmbH, Fernwald (DE) 6,044.628 A * 4/2000 Katayama et al. ............ 53/552
6.427.425 B1* 8/2002 Nakagawa et al. ........... 53/551
(*) Notice: Subject to any disclaimer, the term of this 7,000,366 B2 * 2/2006 Borghi et al. ................. 53,451
patent is extended or adjusted under 35
U.S.C. 154(b) by 11 days. FOREIGN PATENT DOCUMENTS
(21) Appl. No.: 11/237,242 DE 44 25 207 A1 1, 1996
(22) Filed: Sep. 28, 2005
(65) Prior Publication Data * cited by examiner
US 2006/OO64945 A1 Mar. 30, 2006 Primary Examiner Rinaldi I. Rada
Assistant Examiner Paul Durand
(30) Foreign Application Priority Data (74) Attorney, Agent, or Firm—Flynn, Thiel, Boutell &
Tanis, P.C.
Sep. 29, 2004 (DE) ...................... 10 2004 O47 207
(57) ABSTRACT
(51) Int. Cl.
B65B 9/08 (2006.01)
B65B 5L/10 (2006.01) To be able to weld different items, in particular films of
(52) U.S. Cl. .......................... 53/451; 53/551; 53/374.5 different thickness and composition, in an optimized way in
each case, it is proposed in the case of a welding jaw
(58) Field of Classification Search .................. 53/451, circulating along a closed path, for example a transverse
53/452, 52,551, 374.5, 450, 550,552, 75, welding jaw of a vertical tubular bag machine, to provide a
53/373.7, 674.08: 156/580,583.1 sealing time factor (Kt) that can be set as desired within an
See application file for complete search history. open interval from Zero to one and is equal to a quotient of
(56) References Cited a sealing time (ts) and a cycle time (tz) for a circulation of
the welding jaw.
U.S. PATENT DOCUMENTS
3,665,673 A * 5, 1972 Billett et al. .................. 53.441 12 Claims, 8 Drawing Sheets
U.S. Patent Nov. 27, 2007 Sheet 1 of 8 US 7,299,604 B2

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METHOD AND APPARATUS FOR MOVING A great amount of heat to be introduced as a result of their
WELDING UAW great thickness or their multilayered construction. Although
this can be technically remedied in terms of the gearing by
CROSS-REFERENCE TO RELATED using a different coupling or cranking technique, if it is
APPLICATIONS Subsequently intended again to weld a film type that requires
a Smaller amount of heat to be introduced or a shorter bag
This application claims the benefit of German Application length is to be produced, the inflexible, greater sealing time
Ser. No. 10 2004 047 207.6, filed Sep. 29, 2004, which is factor has the effect that the packaging output is reduced,
incorporated herein in its entirety. since too much sealing time is provided, which then pro
10 longs the cycle time. The longer the cycle time is, the fewer
FIELD OF THE INVENTION welding operations can be carried out per minute. For a
cycle time of 1 Sec. 60 tubular bags per minute are trans
The proposed innovation relates to packaging machine versely welded, and consequently produced, on a vertical
construction and in respect thereof to a method for moving tubular bag machine.
a welding jaw, in particular a welding jaw of a transverse 15
sealing station of a vertical tubular bag machine, and also to SUMMARY OF THE INVENTION
a vertical tubular bag machine operated in this way.
The invention is based on the object of being able to weld
BACKGROUND OF THE INVENTION any desired films with greater output and quality.
The object is achieved according to the claims. According
It is known from DE 4425 207A to move a welding jaw to this, a sealing time factor Kt that can be set as desired for
of a transverse sealing station of a vertical tubular bag different bag lengths is preferably predetermined for each
machine along a closed path. In this case, the path has a bag length, is a value in an open interval between Zero and
straight portion, which is provided for making contact with one, preferably between 0.1 and 0.8, which describes which
a film tube pressed together between the welding jaw and a 25 time fraction is provided as a percentage of the cycle time tZ
second, oppositely running welding jaw. In this case, the Zseff for the sealing time along an effective sealing path tz
film tube and the welding jaw are moved further at the same Zseff, and is formed by the equation Kitts/tz. In this case,
speed in the direction of the straight portion, in order to weld the drives are operated in Such a way that the sealing time
the film tube by exposure to the heat of the welding jaws factor Kt is maintained.
within a sealing time. Two drives, acting in directions 30 The proposed method has the advantage that, for a spe
perpendicular to each other and moving the welding jaw, cific bag length, the sealing time factor is set as desired, i.e.
serve for producing a circulating movement of the welding to a suitable or optimum value, depending on the film type
jaw, a complete jaw circulation being achieved within a or depending on the quality requirement for the sealing
cycle time. seam. This can be performed for example by keying in on a
The known method has the disadvantage that, for a 35 display of a packaging machine. If a value which is slightly
specific bag length, it is always definitively prescribed what above Zero is entered (lowest extreme case), only a very
percentage of the cycle time, i.e. the time for a 360° brief application of the welding jaws to a film tube takes
circulation of the welding jaw, is available for the time in place, while considerable time is available for returning the
which the sealing takes place. This sealing time, which welding jaw to carry out a Subsequent welding operation.
generally comprises the period of time during which the 40 This produces a maximum packaging output for example for
welding jaw is in contact with the film tube, that is to say is the case in which an extremely thin, quick-to-weld film of a
welding it, is sometimes also defined for mechanical engi film tube is welded transversely to its transporting direction,
neering reasons in Such a way that it comprises both the and very short bags are produced. If, on the other hand, a
period of time during which the welding jaw is positioned at value which is slightly below one is preselected, the avail
a slight distance away from the film tube, in order to preheat 45 able sealing time is almost as great as the cycle time.
it or cool it by means of cooling air (after welding has taken Considerable time is available for example to reliably weld
place), and the period of time of pressing the welding jaw a particularly thick film, comprising many different layers,
onto the film tube along an effective sealing path (Zseff). transversely to the film transporting direction. The remain
Since the percentage of the cycle time intended for the ing, comparatively small period of time to the completion of
sealing time (however it is defined) is always constant, bags 50 a cycle is then still adequate to return the welding jaw to the
of any length are welded with a fixed percentage, which is beginning of the sealing path, even in the case of very long
referred to as the sealing time factor. Similarly, film types are bags.
always welded with a specific Sealing time factor, irrespec Very high Kt values, for example Kt=0.8, can also be
tive of their thickness and their structure (layers, types of achieved for short bags. If, for short bags, a low film
plastic, layer thicknesses). The sealing time factor is in this 55 transporting speed is chosen, a long sealing time is in this
case kept constant in the same way, irrespective of a case possible.
preselected bag length, since in the known prior art coupling Corresponding activation of the drives provides for this to
elements between two drives acting perpendicularly to each be implemented. Under actual conditions, values of 0.1 to
other provide for this. 0.8 for the sealing time factor are suitable to achieve the
Also, in the case of the known methods, the sealing time 60 maximum machine output. The ideal sealing time factor
factor is kept constant for a constant bag length if there is a respectively for a film type and a specific bag length on a
change of film type. This has the disadvantage that different specific packaging machine may be provided, for example,
film types are welded with different quality, in particular at in the form of a table and be entered in a machine control
relatively high output. Certain film types which are sub system before a new packaging process. Or this control
jected to the constant percentage of the cycle time as a 65 system contains all the necessary data in tabular form, and
sealing time at high output, i.e. with a low cycle time, are no retrieves it if only the film type to be processed and the
longer reliably welded if they in fact require a relatively desired bag length are entered.
 US 7,299,604 B2
3 4
Further, advantageous refinements of the proposed FIG. 5 shows a diagram of the functional relationship
method are described in the claims. between a sealing time factor, which can be chosen as
The method is particularly suitable for operating a vertical desired within an interval, and a bag length, in the case of
tubular bag machine, the welding jaw welding a film tube by two different sealing paths, which is state of the art and can
means of transverse seams, and in each case a tubular bag be realized with the proposed method;
with a specific bag length being severed from the film tube FIG. 6 shows a diagram of a functional relationship
by means of a cutting device. between bag lengths and sealing time factors according to
A particularly great increase in the machine output (bags the proposed method;
per minute) is achieved if, for a given effective, i.e. actual, FIG. 7 shows a diagram of a functional relationship
sealing path Zseff, with increasing bag length a decreasing 10 between bag lengths and sealing paths for selectable Kt
sealing time factor is provided. In an ideal way, the func values according to the proposed method;
tional relationship between the bag length (x axis) and the FIG. 8 shows a diagram of a functional relationship
sealing time factor (y axis) in this case describes a hyper between a cycle time (bags per minute) and an automatic
bole, at least in a partial interval of the range from Zero to sealing time for two different Kt values, a working field for
one. If for a given bag length and a given effective sealing 15 operating a vertical tubular bag machine being defined
path (Zseff), a sealing time factor is selected, for example between the X axis, the y axis and the Kt graphs, and
from a table, or by a computer unit on a packaging machine, FIG. 9 shows a diagram of a functional relationship
a maximum machine output can be correspondingly analogous to that represented in FIG. 8, but with a different
achieved. working field for a different vertical tubular bag machine,
In many cases, customary practice is followed if the the working field being delimited between a graph for
effective sealing path (Zsef) is part of a mechanical engi Kt=0.17, a graph for Kt=0.5 and a graph for Kt=0.25.
neering sealing path (Zs), and the sealing path (Zs) is made
up of a preheating section (Zv) or a stripping section DETAILED DESCRIPTIONS OF THE
(stripping path) known perse for preheating or stripping (by INVENTION
means of a stripping device) the item with the welding jaw 25
at a distance from the item, the actual, effective sealing path In the case of a vertical tubular bag machine 3, a film web
(Zseff) and optionally a cooling section (Zk) for cooling the 14 is drawn off from a supply roll 16 by means of a takeoff
item with the welding jaw at a distance from the item, during 15, drawn over a shaping shoulder 17 and thereby shaped
which cooling air is blown onto the item from a cooling air into a film tube 7 (FIG. 1). The film tube 7 is welded in the
outlet provided at the welding jaw. For the proposed method, 30 transporting direction 19 by means of a longitudinal sealing
it is immaterial how precisely the sealing path is defined. In device 18 and filled by a filling pipe 20. Two circulating
any event, a sealing time which is made available for the welding jaws 1, 6, which can be moved toward each other,
sealing path is used for carrying out the welding. Whether serve the purpose of welding the film tube 7 transversely to
part of the sealing path is used for film preheating and, if the transporting direction 19 by means of transverse seams
appropriate, a further section of the sealing path is used for 35 10. A cutting device 11 in one welding jaw 1 serves the
seam cooling, is immaterial in process engineering terms for purpose of in each case severing a tubular bag 12 with a
the remaining cycle time that is left for returning the welding specific bag length L from the film tube 7.
jaw. Altogether, however, if the mechanical engineering The welding jaws 1, 6 are operated in Such a way that they
sealing path is used instead of the effective sealing path, the circulate in opposite directions, in order to carry out the
sealing time factors become greater (but never equal to one), 40 welding of the film tube 7, which is moved downward at the
and the sealing time should then be defined as the time for same speed as the welding jaws 1, 6, along an effective
the mechanical engineering sealing path. In an analogous sealing path Zseff (FIG. 3). For this purpose, both welding
way, a so-called automatic Sealing time (for a constant film jaws 1, 6 are moved in each case with a point of movement
speed) or a so-called manual sealing time (manually tested A along a closed path 4. Each path 4 has a straight portion
film compression) can also be incorporated in the sealing 45 5, which is provided for making contact with the film tube
time factor. 7 pressed together between the welding jaws 1, 6. In this
case, the film tube 7 and the welding jaw 1 are moved further
BRIEF DESCRIPTION OF THE DRAWINGS at a constant speed in the direction of the straight portion 5.
in order to weld the film tube 7 by exposure to the heat of
The proposed method and a vertical tubular bag machine 50 the welding jaws 1, 6 within a sealing time ts.
that can be operated by the proposed method are described Two drives 8, 9, which are designed as linear drives with
in more detail below on the basis of figures representing in each case a driving part 21 and a moving part 22, act in
exemplary embodiments, in which: directions 23, 24 that are perpendicular to each other and
FIG. 1 shows a side view of a vertical tubular bag machine move a welding jaw 1, are provided to achieve a circulation
with welding jaws of a transverse sealing station that can be 55 of the welding jaw 1 within a cycle time tz. The second
moved toward each other; welding jaw 6 is moved in a way analogous to this.
FIG. 2 shows a side view of two drives, acting perpen Before the tubular bag machine 3 is operated, a sealing
dicularly to each other, for moving a point A of one welding time factor Kt, which can be set as desired and is a value in
jaw of FIG. 1 along a circulating path; an open interval between Zero and one, preferably between
FIG.3 shows a schematic representation of the circulation 60 0.1 and 0.8, is entered in a display of the machine. This
of two welding jaws, which can be moved toward each other describes which time fraction is provided as a percentage of
and weld the film tube of FIG. 1 along an effective sealing the cycle time tz for the sealing time ts along the effective
path Zseff sealing path Zseff. It is formed by the equation Ktts/tz.
FIG. 4 shows a schematic representation of the welding Then, the drives 8, 9 are operated on the basis of stored
jaw circulation corresponding to FIG. 3, but with an effec 65 values in Such a way that the sealing time factor Kt is
tive sealing path reduced by a preheating section and a maintained. A sealing path Zs of 78 mm or a sealing path Zs
cooling section; of 98 mm may be prescribed as the stored value (FIG. 5). On
 US 7,299,604 B2
5 6
the basis of a specific film type to be processed for a sealing 190 ms (milliseconds) being available for the automatic
path Zs of 78 mm, the sealing time factor Kt is selected as sealing time. Very long sealing times can be achieved by
0.5. Consequently, relatively short bags, the length L of increasing the Kt value from 0.5 to 0.6. The abrupt increase
which is intended to be 180 mm, can be produced much in sealing time possible as a result allows the automatic
more quickly than in the case of a conventional tubular bag 5 sealing time to be increased from 500 to 600 msec, for
machine, the sealing time factor Kt of which has a value of example for a number of cycles of 60 bags per minute, in
0.3 for all bag lengths L. If relatively long tubular bags 12 order in this way also to be able to weld relatively thick films
with a bag length L of 500 mm are to be produced, and a reliably. The machine type is designed for the production of
section of 98 mm is provided as the sealing path Zs, a sealing up to 160 bags per minute.
time factor Kt of 0.2 is set. In comparison with a known 10 In the case of another machine type (FIG. 9), a maximum
technique, in which Kt=0.3 time is then gained for the of 140 bags per minute are produced. The working field is
return of the welding jaws 1, 6 for a new transverse welding delimited by three graphs for Kt–0.17, Kt=0.25 and Kt=0.5.
operation on the film tube 7. On the other hand, the time for Kt=0.25 corresponds for example to a conventional operat
return was comparatively low in the case of the short tubular ing mode. An increase to Kt=0.5 has the effect of achieving
bag 12. In both cases (short and long tubular bags 12), an 15 much higher sealing times tsaut than were previously known
increase in output of the tubular bag machine 3 was for numbers of cycles of 40 to almost 100 bags per minute.
achieved. In the first case (shortbag) because of a shortening A much longer sealing time tsaut than 800 ms (0.8 sec) is not
of the return time along the bent portion of the path 4 and in envisaged in the case of this machine type either.
the second case (long bag) because of a lengthening of this 1 welding jaw
portion, though in fact because of a sealing time factor Kt 2 transverse sealing station
prescribed for the bag length L. An optimum output (bags 3 tubular bag machine
per minute) is achieved if the tubular bag machine 3 is 4 path
always operated in Such a way that, for a given effective 5 straight portion
sealing path Zseff, with increasing bag length La decreasing 6 oppositely running welding jaw
sealing time factor Kt is provided. Otherwise, the return 25 7 film tube
operation would generally not take place quickly enough, 8, 9 drive
and consequently there would be a time loss (loss of output). 10 transverse seam
While in the case of this exemplary embodiment, for a given 11 cutting device
bag length L and a given effective sealing path Zseff, a 12 tubular bag
sealing time factor Kt is selected (FIG. 4), the effective 30 13 cooling air output
sealing path Zseff may also be part of a mechanical engi 14 film web
neering sealing path Zs (FIG. 5). Then the sealing path Zs is 15 takeoff
made up of a preheating section Zv for preheating the film 16 supply roll
tube 7 with the welding jaws 1, 6 at a distance from the film 17 shaping shoulder
tube 7, the actual, effective sealing path Zseff and optionally 35 18 longitudinal sealing device
a cooling section Zk for cooling the film tube 7 with the 19 transporting direction
welding jaws 1, 6 at a distance from the film tube 7, during 20 filling pipe
which cooling air is blown onto the film tube 7 from a 21 driving part
cooling air outlet 13 respectively provided at the welding 22 moving part
jaws 1, 6. In this case the sealing time tS is defined as the 40 23, 24 direction
time for the mechanical engineering sealing path Zs. 25 guide
With the method according to the invention, a constant A point of movement
sealing time factor Kt can be preselected independently of L bag length
the bag length L (FIG. 6). Moreover, relatively high sealing Kt=ts/tz sealing time factor
time factors Kt can be achieved. The higher the Kt value 45 ts sealing time
(FIG. 7), the longer the sealing paths Zs available. For tZ cycle time
example, given a bag length L of 300 mm, instead of a Kt Zs sealing path, technical
value of 0.35 (the maximum achieved in the case of the Zseff effective sealing path
known prior art), the Kt value can be increased to 0.8. As a The invention claimed is:
result, instead of a sealing path Zs of about 110 mm, a much 50 1. Method for moving a welding jaw of a transverse
higher sealing path Zs of 240 mm is available. sealing station of a vertical tubular bag machine, comprising
The two drives 8, 9 are electromagnetic linear drives. the steps of:
They operate as linear motors. Their movable parts 22 hover a welding jaw being moved along a closed path, said path
along the driving parts 21 on the principle of magnetic having a straight portion, which is provided for the
levitation. In this case, a moving part 22 of a drive 8, 9 is 55 welding jaw to make contact with a film tube to be
respectively guided along a guide 25 of the driving part 22 welded, pressed together between the welding jaw and
of the drive 8, 9. By superposing the movements of the a second, oppositely running welding jaw,
drives 8, 9, which are moved in directions 23, 24 perpen the film tube and the welding jaw being moved further at
dicular to each other, all the positions of the point of the same speed in the direction of the straight portion,
movement A on the closed path 4 can be produced. Simi 60 in order to weld the film tube by exposure to the heat
larly, the path 4 can be correspondingly modified. of the welding jaw within a sealing time (ts), and
The proposed tubular bag machine 3 can be operated two electromagnetic linear drives, acting in different
within working fields (FIG. 8, FIG. 9), an automatic sealing directions that are perpendicular to each other and
time tsaut being respectively selectable for a number of moving the welding jaw, the drives being operated to
cycles Q. In this case, Kt values that can be fixed determine 65 achieve a circulation of the welding jaw within a cycle
the limits of this working field. In FIG. 8, accordingly, 160 time (tz), wherein a sealing time factor (Kt), that can be
bags per minute can be achieved for Kt=0.5, a maximum of set as desired for different bag lengths (L), is a value in
 US 7,299,604 B2
7 8
an open interval between Zero and one that describes a further at the same speed in the direction of the straight
time fraction of the sealing time (ts) as a percentage of portion, in order to weld the film tube by means of
the cycle time (tz) along an effective sealing path transverse seams by exposure to the heat of the welding
(Zseff), as described by the equation Ktts/tz, and jaw within a sealing time (ts);
wherein the drives are operated in such a way that the 5 two electromagnetic linear drives, acting perpendicularly
sealing time factor (Kt) is maintained. to each other and connected to the welding jaw to
2. Method according to claim 1, wherein the welding jaw achieve a circulation of the welding jaw within a cycle
welds said film tube by means of transverse seams, and time (tz), such that a sealing time factor (Kt), described
whereby a tubular bag with a bag length (L) is severed from by the equation Kitts/tz, has a value between Zero and
the film tube by a cutting device. 10 one, and is maintained as a constant; and
3. Method according to claim 2, wherein for a given a cutting device for severing a tubular bag with a bag
effective sealing path (Zseff), with increasing bag length (L) length (L) from the film tube.
a decreasing sealing time factor (Kt) is provided. 8. Apparatus according to claim 7, wherein a driving part
4. Method according to claim 2, wherein for a given bag of one of said two drives is connected to a moving part of
length (L) and a given effective sealing path (Zseff), a 15 another of said two drives.
sealing time factor (Kt) is selected. 9. Apparatus according to claim 7, wherein for a given
5. Method according to claim 1, wherein the effective effective sealing path (Zseff), with increasing bag length (L)
sealing path (Zsef) is part of a mechanical engineering a decreasing sealing time factor (Kt) is provided.
sealing path (Zs), and wherein the mechanical engineering 10. Apparatus according to claim 7, wherein for a given
sealing path (Zs) is made up of a preheating section (Zv) for bag length (L) and a given effective sealing path (Zseff), a
preheating the film tube or a stripping section for stripping sealing time factor (Kt) is selected.
the film tube with the welding jaw at a distance from the film
tube, the effective sealing path (Zseff) and a cooling section 11. Apparatus according to claim 7, wherein the effective
(Zk) for cooling the film tube with the welding jaw at a sealing path (Zsef) is part of a mechanical engineering
distance from the film tube as cooling air is blown onto the 25 sealing path (Zs), and the mechanical engineering sealing
film tube from a cooling air outlet provided at the welding path (Zs) is made up of a preheating section (Zv) for
JaW. preheating the film tube or a stripping section for stripping
6. Method according to claim 5, wherein the sealing time the film tube with the welding jaw at a distance from the film
(ts) is defined as the time for the mechanical engineering tube, the effective sealing path (Zsef) and optionally a
sealing path (Zs). 30 cooling section (Zk) for cooling the film tube with the
7. Apparatus in the form of a vertical tubular bag machine, welding jaw at a distance from the film tube as cooling air
comprising: is blown onto the film tube from a cooling air outlet provided
a welding jaw configured for movement along a closed at the welding jaw.
path, said path having a straight portion, which is 12. Apparatus according to claim 11, wherein the sealing
provided for the welding jaw to make contact with a 35 time (ts) is defined as the time for the mechanical engineer
film tube to be welded, pressed together between the ing sealing path (Zs).
welding jaw and a second, oppositely running welding
jaw, wherein the film tube and the welding jaw move