EP0732293A2 - Method for the optimization of the operating efficiency of a folding machine - Google Patents

Abstract

The automated process is used for the folding of sheet material to create envelopes or folders. The individual sheets of material are extracted from a stack by a suction roller Ä16Ü and are fed in sequence by a conveyor Ä11Ü to a station Ä12Ü where folds are made to form the pocket part. A further station receives the part formed product and carries out the forming of the flap. The spacing of the continuously fed sheets is closely controlled and for this purpose a number of sensors ÄB1-B7Ü are used to monitor different stages in the cycle. Some of the sensors are edge detectors ÄB2, B4, B6, B7Ü. The sensor signals are received by the controller Ä10Ü to obtain a minimum distance between successive sheets.

Description

The invention relates to a method for optimizing the operating performance of a folding machine with a sheet feeder and a plurality of successive folding stations by means of a central control device, in which signals from sheet detectors are processed, which are arranged at different points of the folding machine along the sheet path.

To optimize the folding performance in a folding machine with several successive folders, the sheet spacing between two successive sheets must be set as small as possible. However, the sheet spacing is a critical quantity, because a sheet spacing that is too small leads to disruptions in the folding operation. In order to reliably prevent the folding machine from being switched off by such faults, a relatively large sheet spacing has so far been chosen, but this represents a loss of possible folding performance.

To optimize the folding performance, the transport distance between two folding sheets should be as small as possible. However, the minimum sheet spacing must be so large that a folded sheet has completely disappeared from the sheet entry zone of a folding machine before the next sheet can enter this zone.

The object of the invention is to develop a method which guarantees the sheet spacing required on the folding machine and automatically adjusts the sheet spacing on the suction wheel in order to optimize the operating performance of the folding machine.

The invention is based on the consideration that a learning process or a control can be used for the setting of the minimum sheet distance if the folding machine has a central control device in which signals from sheet detectors are processed which are located at various critical points along the folding machine Sheet run section are arranged, in particular in the area of the sheet inlet of the respective folding units.

According to the invention, the method is characterized in that the time interval between the trigger pulses supplied to the sheet feeder is set to the smallest possible value, in particular regulated, in which a predetermined minimum distance between two pulse edges of the sheet detectors, the first of which is the trailing edge of a preceding sheet Sheet entry of a folding station and the second represents the leading edge of the following sheet is not undercut.

For a purely pocket folding machine, the entry situation at the first folder is decisive for determining the shortest sheet spacing. In the case of a combination of pocket and sword folding units, the running-in situation at the first sword folding unit must also be taken into account.

In one embodiment with a sword folding unit, the two pulse edges are preferably emitted by a sheet detector at the sheet inlet of the sword folding unit, which is arranged at a predetermined distance behind an upstream sheet detector which can be adjusted to the sheet length and whose pulse signal detects the trailing edge of a sheet to drive the folding blade for triggers a folding process. This upstream sheet detector is set on the rear edge of a sheet aligned at the stop of the sword folding mechanism.

In an embodiment with a pocket folding unit, the two pulse edges are emitted by a pair of sheet detectors on the pocket folding unit, the first pulse edge corresponding to the leading edge of a sheet at the sheet inlet and the second pulse edge corresponding to the rear edge of a sheet emerging from a folding pocket.

In one embodiment for a folding machine with several folding units, in particular a combined machine with pocket folding units and sword folding units, an associated minimum distance between two pulse edges of the pulse signals emitted by the sheet detectors at the respective sheet inlet and the distance between the triggering pulses for the sheet feeder are specified for the different folding units regulated in such a way that none of the specified minimum distances is undershot.

To avoid damage due to excessive wear, the maximum sheet throughput speed is limited to a predetermined value. A further increase in the operating performance of the folding machine can be achieved according to a particular aspect of the invention in that the sheet throughput speed is increased beyond the predetermined limit value for relatively long sheets to be folded, since the long sheet length results in a shorter cycle of the sheets and the load the folding machine is correspondingly lower. In particular, a single sheet is called up as a learning sheet before production begins and runs through all folding stations; the sheet length is determined from the signals emitted by the sheet detectors, and the sheet throughput speed of the folding machine is set to the greatest possible value, at which neither a predetermined limit of the sheet throughput rate nor a predetermined limit value arising from sheet length, sheet spacing and sheet throughput rate is determined resulting cycle sequence of the sheet feeder is exceeded.

From DE 40 13 401 A1 a method for setting up and controlling a folding machine is known, in which a sample sheet passes through the folding machine, so that the length of the sample sheet is measured with a displacement sensor coupled to a drive element of the machine, which is then used to monitor and control the Target arc length is used. In contrast to this, the method according to the invention provides that the arc length of the learning arc is determined by signals emitted by the arc detectors, whereby the arc length can be determined even more precisely.

In order to optimize the operating performance, previously known folding machines are either set so that they do not exceed the maximum sheet throughput speed of the folding machine for a certain sheet length or they are set so that the maximum cycle sequence of the sheet feeder is not exceeded for a certain sheet length. In contrast, the method according to the invention provides that both the sheet throughput speed of the folding machine does not exceed a predetermined limit, nor a predetermined limit value that is exceeded from the sheet sequence of the sheet feeder resulting from sheet length, sheet spacing and sheet throughput speed. The operating performance of a folding machine can only be optimized by taking both limit values into account, since it can no longer occur that a folding machine has a too high cycle sequence with a tolerable sheet throughput speed or a folding machine with a high, but acceptable cycle sequence has an excessively high sheet throughput speed, so that damage to the folding machine or waste occurs.

According to a further preferred embodiment of the method, in which a single sheet is called up as a learning sheet and goes through all folding stations before production begins, it is provided that up to a certain value of the cycle sequence, the sheet throughput speed does not exceed a predetermined absolute limit value and above this value the Cycle sequence the sheet throughput speed is set to a value which is smaller than the absolute limit as the cycle sequence increases. In the case of high cycle sequences and high throughput speeds, there is a combination load for the folding machine due to the high sheet throughput speed and the high cycle sequence. This combination load is avoided by reducing the limit value for the sheet throughput speed as the cycle sequence increases.

Fig. 1a

eine schematische Ansicht eines Taschenfalzwerkes mit einem sich darin befindlichen Bogen bei Falzbeginn,

Fig. 1b

das Taschenfalzwerk gemäß Fig. 1a mit dem fertiggefalzten Bogen,

Fig. 2a

ein Schwertfalzwerk mit einem sich darin befindlichen Bogen bei Falzbeginn,

Fig. 2b

das Schwertfalzwerk gemäß Fig. 2a mit dem fertiggefalzten Bogen,

Fig. 3

ein kombiniertes Taschen- und Schwertfalzwerk mit zahlreichen Bogendetektoren zur Durchführung des erfindungsgemäßen Verfahrens,

Fig. 4

einen Teil des im Kombinations-Falzwerk nach Fig. 3 enthaltenen Taschenfalzwerkes,

Fig. 5

in perspektivischer Ansicht ein im Kombinations-Falzwerk nach Fig. 3 einsetzbares Schwertfalzwerk,

Fig. 6

in Gegenüberstellung die Schaltzustände der im Kombinations-Falzwerk nach Fig. 3 vorgesehenen Bogendetektoren sowie die Schaltzustände von einigen weiteren darin enthaltenen Einrichtungen bei Durchführung des erfindungsgemäßen Verfahrens,

Fig. 7a

ein Diagramm zur Darstellung der maximalen Werte für die Bogentakte und die Bogen-Durchlaufgeschwindigkeiten einer Kombinations-Falzmaschine bei Durchführung des erfindungsgemäßen Verfahrens, und

Fig. 7b

ein Diagramm zur Darstellung der maximalen Werte für die Bogentakte und Bogen-Durchlaufgeschwindigkeiten einer Taschenfalzmaschine bei Durchführung des erfindungsgemäßen Verfahrens.

An embodiment of the method will now be described with reference to the accompanying drawings.
In these shows:

Fig. 1a

1 shows a schematic view of a pocket folding unit with a sheet located therein at the start of folding,

Fig. 1b

the pocket folding unit according to FIG. 1a with the finished folded sheet,

Fig. 2a

a sword folder with a sheet inside it at the start of folding,

Fig. 2b

2a with the finished folded sheet,

Fig. 3

a combined pocket and sword folder with numerous sheet detectors for carrying out the method according to the invention,

Fig. 4

part of the pocket folding unit contained in the combination folding unit according to FIG. 3,

Fig. 5

3 is a perspective view of a sword folding unit which can be used in the combination folding unit according to FIG. 3,

Fig. 6

in comparison, the switching states of the sheet detectors provided in the combination folding unit according to FIG. 3 and the switching states of some further devices contained therein when the method according to the invention is carried out,

Fig. 7a

a diagram showing the maximum values for the sheet cycles and the sheet throughput speeds of a combination folding machine when performing the method according to the invention, and

Fig. 7b

a diagram showing the maximum values for the sheet cycles and sheet throughput speeds of a pocket folding machine when performing the method according to the invention.

To optimize the folding performance of one of the fig. 1a and 1b pocket folding mechanism shown, the sheet spacing between two successive sheets must be set as small as possible. FIG. 1a shows a sheet that has run into the folding machine at the beginning of the folding and is finally finished folded in FIG. 1b. Faults in the folding operation occur when the subsequent sheet shown in FIG. 1b enters the folding machine too early, namely when the leading sheet has not yet been fully folded. The folded, leading sheet must be completely out of the sheet entry zone must have disappeared from the folding machine before the subsequent sheet can enter this zone.

The same applies to a sword folding mechanism shown in FIGS. 2a and 2b. 2a shows the start of folding of a sheet that has just entered and FIG. 2b the end of folding of this sheet when it has left the sheet entry zone, so that a subsequent sheet can run in.

3 shows a combination folding machine consisting of a pocket folding unit 12 and an adjoining sword folding unit 14. A suction wheel 16 arranged in front of the pocket folding unit 12 as part of a sheet feeder 20 transports sheets of paper from a container to a conveyor line which comprises an alignment table. A specific suction cycle Y1 for the suction wheel 16 is determined by a central control device 10 of a digital control system. Sheet detectors B1, B2, B4 to B7 are arranged at various points in the combination folding machine and are covered during the sheet pass and in the meantime deliver the signal level on and during the sheet break the signal level off, as will be described in more detail with reference to FIG. 6. Reference number B3 denotes an incremental encoder which is mechanically connected directly to the folding roller drive, so that 1 mm of paper transport corresponds to a certain number of pulses. The reference number 11 denotes the sheet inlet of the pocket folding mechanism 12 and the reference number 13 the sheet outlet of the same.

The entire sensors and actuators of the folding machine are linked in the control device 10 of the digital control system. In addition to the general machine functions, the controller evaluates the signals from the sheet detectors B1, B2, B4, B5, B6, B7 and the incremental gear B3 and controls the suction cycle Y1 of the suction wheel 16 and the sword cycle Y2, Y3.

The sheet detector B1 is located in the immediate vicinity of the suction wheel 16, the sheet detector B2 at the sheet inlet of the pocket folding mechanism 12 and the sheet detector B4 at the pocket inlet of a first folding pocket. The sheet detector B5 is arranged at the sheet outlet of the pocket folding unit 12. The sheet detector B5 introduces the signal level from the time the sheet enters until it disappears from the folding zone. Only when the sheet detector B5 is at the off signal level is the next sheet allowed to enter the folding zone of the pocket folding unit 12.

Sheet detectors B6 and B7 are fastened on a format-adjustable holder in a sword folding mechanism 14 adjoining the pocket folding mechanism 12. The holder (see FIG. 5) is adjusted so that the trailing edge of the folded sheets transported to the stop of the sword folding mechanism 14 no longer cover the sheet detector B6. The position of the sheet detectors B2, B4 and B5 is more precise in FIG. 4 and the position of the sheet detectors B6, B7 and the holder is shown more precisely in FIG. 5. After entering the sheet, the falling stroke of the sheet detector B6 acting as a signal generator triggers the heavy stroke. The sheet detector B7 introduces the signal level from the time the sheet enters until it disappears from the folding zone. The next sheet can only enter the folding zone of the sword folding mechanism 14 when the sensor B7 has the signal level Off.

A minimum sheet clearance must be maintained both on the pocket folding unit 12 and on the sword folding unit 14 so that the folding process functions properly.

The suction cycle control is preset to the correct cycle distance by means of a learning sheet, so that the minimum ground clearance on the pocket and sword folding mechanism 12, 14 is maintained. A percentage safety margin is added to the measured minimum distance.

The central control device 10 uses the signal curves of the sheet detectors B2, B4, B5, B6, B7 and the signals of the incremental encoder B3 to calculate the correct arc distance on the suction wheel 16. The positions of the arc detectors B1, B2 and B4 to B7 together with the incremental encoder B3 are used in the calculation considered. The corresponding signal profiles of the sheet detectors including incremental encoders are shown in FIG. 6 for a specific sheet format and a type of fold.

In Fig. 6, the suction stroke setting determined by the learning curve, which is normally maintained during production, is designated Y1. S1 is the suction cycle period. B1, B2 and B4 to B7 represent the signal levels of the corresponding arc detectors. S2 denotes the arc distance on the suction wheel, S3 the arc distance in the folding pocket of the pocket folding mechanism 12 and S4 the arc distance on the sword folding mechanism 14. Y2 and Y3 represent the switching states of a sword clutch or a sword brake, which are not explicitly shown in FIG. 3.

The operating performance of the folding machine shown in FIG. 3 is optimized in that the signals of the sheet detectors B1, B2 and B4 to B7 and of the incremental encoder B3 are processed by the control device 10 as follows: the time interval between the trigger pulses fed to the sheet feeder 20 is based on the regulates the smallest possible value at which a predetermined minimum distance between two pulse edges of the arc detectors B2 and B4 is not undershot. The first pulse edge is the trailing edge of a preceding sheet at the sheet inlet 11 of the pocket folder 12 and the second pulse edge is the leading edge of the following sheet. The first pulse edge in the arrangement of the sheet detectors B1, B2 and B4 to B7 shown in FIG. 3 corresponds to the front edge of a sheet following a first sheet at the sheet inlet 11, the corresponding signal being indicated by the Arc detector B2 is generated. The second pulse edge corresponds to the rear edge of a preceding sheet emerging from a folding pocket, which is scanned by the sheet detector B4. The sheet spacing S3 determined in this way (see FIG. 6) at the pocket folding unit 12 is, as mentioned, regulated under constant control to the smallest possible permissible value. This can ensure that a subsequent sheet does not enter pocket folding mechanism 12 too early.

A corresponding sequence results for the sword folding mechanism 14. The sheet detector B7 at the sheet inlet of the sword folding unit 14 delivers a pulse, the flank of which is assigned to the trailing edge of a preceding sheet. The sheet detector B6 in turn delivers a pulse with an edge which is assigned to the leading edge of a subsequent sheet. The sheet spacing S4 (cf. FIG. 6) on the sword folding mechanism 14 can be determined from the corresponding difference. The pulse signal upon detection of the trailing edge of the preceding sheet triggers the drive of the folding blade for a folding process, as can be clearly seen in FIG. 5, in that the sword clutch is switched on by the signal Y2 and the sword brake by the signal Y3 is brought into the off state. This method optimizes the operating performance of the sword folding mechanism 14 and thus also of the entire combination folding machine, since it is impossible for the folding sword to be triggered at the wrong time and for the subsequent sheet to enter the sword folding mechanism 14 too early.

A further optimization of the operating performance is to measure the actual minimum distances during the running production and to reduce or increase the arc distance S2 on the suction wheel 16 by means of a trend determination.

If the bow distance is undershot (malfunction), a swing stroke for the bow already under the sword is prevented and the machine is stopped immediately.

Furthermore, the determined sheet lengths are used for sheet throughput control.

The sheet detectors B2 and B4 are also used to check that the sheet is fully fed into the folding pocket.

• a) Tascheneinlaufkontrolle
  Mit der Vorderkante des einlaufenden Bogens an B2 (Signal B2 springt von Aus nach Ein) wird ein Zähler in der Steuerung um 1 hochgezählt und an B4 um 1 heruntergezählt. Bei einem nicht in die Tasche einlaufenden Bogen wird der Zählerstand größer 1. Der Falzmaschinenantrieb wird sofort ausgeschaltet.
• b) Taschenanschlagkontrolle
  Ein nicht bis zum Taschenanschlag laufender Bogen wird nicht richtig gefalzt und führt, zu Produktionsstörungen. Mittels des Lernbogens wird der Weg des einlaufenden und auslaufenden Bogens gespeichert und als Referenzwert für die Falzbogen in der Produktion herangezogen. Der Vorteil der Tascheneinlaufkontrolle ist, daß ein verfalzter Bogen frühzeitig erkannt wird und der Falzwerkantrieb schnell abgeschaltet werden kann.

The signals emitted by the sheet detectors B2 and B4 can be processed in the control device 10 for two further functions:

• a) Pocket entry control
  With the leading edge of the incoming sheet at B2 (signal B2 jumps from off to on), a counter in the controller is incremented by 1 and counted down by 1 at B4. If the sheet does not enter the pocket, the counter reading becomes greater than 1. The folding machine drive is switched off immediately.
• b) Pocket stop control
  A sheet that does not run to the pocket stop is not folded properly and leads to production disruptions. The path of the incoming and outgoing sheets is saved by means of the learning sheet and used as a reference value for the folded sheets in production. The advantage of pocket entry control is that a folded sheet is recognized early and the folder drive can be switched off quickly.

The second method described below can be used in addition to the previously described methods in order to optimize the operating performance of a folding machine, as is shown, for example, in FIG. 3. However, the method can also be used separately in a combination folding machine, as shown in FIG. 3, in order to optimize its operating performance.

The method described above and that described below are not limited to combination folding machines, but can also be used in pocket folding machines or sword folding machines and also lead to better operational performance there.

The second procedure for optimizing operational performance works as follows: before production starts, a single sheet is called up as a learning sheet, which runs through all folding stations. Signals are emitted from the various sheet detectors, from which the sheet length is determined in the control device 10. The sheet throughput speed of the folding machine is set to the greatest possible value, at which neither a predetermined limit of the sheet throughput speed, nor a predetermined limit value, which results from the sheet length, sheet spacing and sheet throughput speed of the sheet feeder, also in the central control device 10 is determined, is exceeded.

For a specific combination folding machine, this is shown graphically in FIG. 7a for a predetermined minimum distance and different sheet lengths. This folding machine has a limit for the maximum sheet cycle of 30,000 cycles / min, as well as a predetermined absolute limit for the maximum sheet throughput speed of 230 m / min and a predetermined limit for the sheet throughput speed of 180 m / min for small sheet lengths. In the case of small arc lengths, an arc cycle / arc throughput speed ratio results, as is shown by the steepest straight line, with a predetermined minimum distance. Although the sheet cycle could be extremely increased in the case of small sheet lengths, the predetermined limit value for the cycle sequence of the sheet feeder 20 of 30,000 sheet cycles / min must not be exceeded in the combination folding machine. The sheet feeder 20 can thus be set to 30,000 sheet cycles / minute, for example, and the sheet throughput speed the folding machine can be maximized to 180 m / min, so that there is a larger sheet spacing. This is possible because both predetermined limits, namely that for the sheet cycle and that for the sheet throughput speed, are not exceeded.

Depending on the length of the bend, there is a different ratio of the bend rate to the bend throughput speed at a predetermined minimum distance, which is reflected in more or less steep straight lines in FIG. 7a. With longer arc lengths, the line becomes correspondingly flatter.

The sheet throughput speed of the combination folding machine can only be set to the largest possible value which allows neither the predetermined limit of the sheet throughput speed of 180 m / min for small sheet lengths, nor the predetermined limit value for the cycle sequence of the sheet feeder 20 of 30,000 sheet cycles / min is exceeded. In the case of large sheet lengths in which the sheet cycle cannot reach the predetermined limit anyway, the sheet throughput speed can be increased accordingly, but only up to the absolute limit of 230 m / min.

The absolute limit of 230 m / min must not be exceeded, especially with larger sheet lengths, where high sheet throughput speeds are used. At this absolute limit, however, it is not allowed to work with 30,000 sheet cycles / min, but only with 25,000 sheet cycles / min.

If more than 25,000 sheet cycles / min are to be used for medium floor lengths, the limit value for the sheet throughput speed is reduced in order to reduce a combination load on the folding machine from a high cycle sequence and high sheet throughput speed. This change in the limit value is shown in FIG. 7a by the limit line with a negative slope. Up to a value In the cycle sequence of 25,000 sheet cycles / min, the sheet throughput speed must not exceed the specified absolute limit of 230 m / min. Above this value of the cycle sequence, the sheet throughput speed must therefore be set to a value which is smaller than the absolute limit as the cycle sequence increases.

The same applies correspondingly to the course of the predetermined limits for the sheet cycle and the sheet throughput speed for a pocket folding machine, as is shown in a corresponding diagram in FIG. 7b.

Claims (11)

Method for optimizing the operating performance of a folding machine with a sheet feeder (20) and a plurality of successive folding stations by means of a central control device (10) in which signals from sheet detectors (B1, B2, B4 to B7) are processed which are located at various points along the folding machine Sheet passage are arranged, characterized in that the time interval between the trigger pulses supplied to the sheet feeder (20) is set to the smallest possible value, in particular is regulated, in which a predetermined minimum distance between two pulse edges of the sheet detectors (B2, B4; B6, B7), the first of which is the trailing edge of a preceding sheet at the sheet inlet (11) of a folding station and the second of which is the leading edge of the following sheet. Method according to Claim 1, characterized in that the two pulse edges are emitted by a sheet detector (B7) at the sheet inlet of a sword folding unit (14) which is arranged at a predetermined distance behind an upstream sheet detector (B6) which can be adjusted to the sheet length and whose pulse signal triggers the drive of the folding blade for a folding process when the rear edge of a sheet is detected. Method according to claim 1, characterized in that the upstream sheet detector (B6) is adjusted to the rear edge of a sheet aligned with the stop of the sword folding mechanism (14). Method according to Claim 1, characterized in that the two pulse edges are emitted by a pair of sheet detectors (B2, B4) on a pocket folder (12), the first pulse edge of the leading edge of a sheet at the sheet inlet (11) and the second pulse edge of the trailing edge of one corresponds to the preceding sheet emerging from a folding pocket. Method according to one of the preceding claims, characterized in that an associated minimum distance between two pulse edges of the pulse signals emitted by the sheet detectors (B1, B2, B4 to B7) at the respective sheet inlet (11) and the distance between the triggering pulses is specified for several folding stations for the sheet feeder (20) is regulated so that none of the specified minimum distances is undershot. Method according to one of the preceding claims, characterized in that fluctuations in the temporal occurrence of the pulse edges are compensated for by averaging. Method according to one of the preceding claims, characterized in that a single sheet is called up as a learning sheet and all folding stations pass through before the start of production, that the sheet length is determined from the signals emitted by the sheet detectors (B1, B2, B4 to B7) and that the sheet The throughput speed of the folding machine is set to the greatest possible value at which neither a predetermined limit of the sheet throughput speed nor a predetermined limit value of the cycle sequence of the sheet feeder (20) resulting from sheet length, sheet spacing and sheet throughput speed is exceeded. Method for optimizing the operating performance of a folding machine with a sheet feeder (20) and a plurality of successive folding stations by means of a central control device (10), in which signals from sheet detectors (B1 to B7) are processed, which are arranged at various points on the folding machine along the sheet passage, a single sheet being called up as a learning sheet and going through all the folding stations before production begins, characterized in that the sheet length is determined from the signals emitted by the sheet detectors (B1, B2, B4 to B7) and that the sheet throughput speed of the folding machine is as large as possible Value is set at which neither a predetermined limit of the sheet throughput speed nor a predetermined limit value of the cycle sequence of the sheet feeder (20) resulting from sheet length, sheet spacing and sheet throughput speed is exceeded. A method according to claim 8, characterized in that up to a certain value of the cycle sequence, the sheet throughput speed does not exceed a predetermined absolute limit value and above this value of the cycle sequence, the sheet throughput rate is set to a value which is less than that absolute limit as the clock sequence increases. A method according to claim 8, characterized in that above a certain value of the sheet length, the predetermined limit of the sheet throughput speed has a substantially greater value than below the certain value of the sheet length. Method according to one of claims 8 to 10, characterized in that the time interval between the triggering pulses supplied to the sheet feeder (20) is set to the smallest possible value, in particular is regulated, in which a predetermined minimum distance between two The pulse edges of the sheet detectors (B2, B4), the first of which is the rear edge of a preceding sheet at the sheet inlet (11) of a folding station and the second of which is the front edge of the following sheet, are not undercut.

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