EP1647373B1 - Method for cutting more sides of a printed product - Google Patents

Abstract

The cutting device (1) comprises a storage unit (1) for the supply of objects (5) to be cut and a feeding device (7) moving the objects (5) to the cutting station (17). The cutting station (17) is equipped with a pressure element (19) holding the object (10) in a clamped position on a cutting table (18) and with three blades (23, 24). The feeding device (7) and the cutting station (17) are directed by a control unit (30) in order to facilitate variable combinations of feeding, pressing, and cutting with a constant time used for the cutting motion and a variable duration as required for feeding and pressing.

Description

The invention relates to a method according to the preamble of claim 1 and a cutting device according to the preamble of claim 8 for trimming a plurality of edges of a printed product.

For cutting material to be cut, for example, brochures, book blocks or the like, three-knife trimmer are known in which the material to be cut is cut against cutting strips. Such three-knife trimmers are able to truncate in the same position a stack consisting of at least one book or book block completely and on all three sides. For this purpose, the cut-to-cut material to be cut is aligned on a cutting table and is trimmed on the head and foot as well as on the front. Depending on the design of the three-knife trimmer, the cutting sequence can also be reversed.

During the cutting process, the material to be cut is pressed against the cutting table with a press ram, so that it can not shift due to the cutting forces that occur. To ensure that the geometry of the material to be cut remains stable during the cutting process, it must be ensured that all air that is still freshly bound is removed Cutting material is located, can escape. Air that is in the cut during the cutting process is harmful in several ways. On the one hand, the friction value between the blades is reduced by the action of the air as air cushion, whereby the layers can shift each other during the cutting process. Secondly, because of the trapped air, the cut material is too thick, which increases the deflection of the cut material in the area of the cuts, so that the upper layers of the cut material are cut longer. Both effects affect the quality of the cut.

A method for cutting cut material is for example from DE 42 06 329 A known. In this case, a pressing device is used, in which a drive for pressing elements, taking into account the lowest building mass according to a predetermined characteristic is adjustable. The lifting movement of the pressing element is preselected depending on the application height of the material to be cut. Also provided is a Presskraft- and Hubhöhenauswahl, in which an operator enters the desired pressing force and lifting height. However, the problems with trapped air and correspondingly reduced cutting quality are not solved there.

Next discloses the EP 0 740 983 A a three-knife trimmer according to the preamble of claim 8 and a method according to the preamble of claim 1, in which two side knives and a front knife have separate drives with digitally controlled servo or stepper motors. The movements of the knives are synchronized by a common control computer. A ram also has a separate drive with a digitally controlled servo or stepper motor and is synchronized. Thereby should the mechanical complexity and the space required for the coupling elements can be reduced.

The DE 30 11 090 A discloses a cutting device with a mechanically driven pressing device, in which the pressing force is hydraulically adjustable. The pressing device is automatically positioned according to the respective preceding crop height.

The invention has for its object to provide a method and a device for trimming multiple edges of a printed product, which allows a higher quality of cut.

The object is achieved in a method having the features of claim 1 and in a device having the features of claim 8.

Fig. 1

schematisch eine Ansicht einer erfindungsgemässen Schneideinrichtung,

Fig. 2

ein Diagramm, das bei maximal möglicher Taktzahl bei einem Verarbeitungszyklus die Schritte des Transportes, der Pres- sung, des Front- und des Kopf-/Fussschnittes zeigt,

Fig. 3

ein Diagramm gemäss Fig. 2, jedoch mit doppelter Zykluszeit,

Fig. 4

ein Diagramm gemäss Fig. 3, mit verlängerter Presszeit und

Fig. 5

ein Diagramm zur Illustration von Bauschigkeit und Abhängigkeit der Dicke von der Presskraft zur Ermittlung der Federkennlinie des Schneidgutes.

Subsequently, the invention will be explained with reference to the drawing, to which reference is made with respect to all unspecified details in the description, based on an embodiment. In the drawing show:

Fig. 1

1 is a schematic view of a cutting device according to the invention;

Fig. 2

a diagram showing the maximum possible number of cycles in a processing cycle, the steps of transport, the pres- solution, of the front and the head / foot cut,

Fig. 3

a diagram according to Fig. 2 but with twice the cycle time,

Fig. 4

a diagram according to Fig. 3 , with extended press time and

Fig. 5

a diagram illustrating the bulkiness and dependence of the thickness of the pressing force to determine the spring characteristic of the material to be cut.

In the Fig. 1 Cutting device 1 shown here has a feed device 2 indicated here, a feed device 7, as well as a cutting device 17 for printed products, mainly book block or books. The feeding device 2 has a per se known conveying means with which the printed products 5 are fed in accordance with the direction of arrow 60 to a stacking device 4 and form a stack of printed products 5 there. The material to be cut 10 consists of at least one printed product 5. Printed products are for example magazines, catalogs, paperbacks or the like. Printed matter. The printed products produced within a production may vary in thickness.
The maximum set to the height of the smallest thickness of the material to be cut 10 pusher 3 pushes the material to be cut from the stacking device 4 in the feeder 7, which consists essentially of a lower take-off roll 9 and an upper take-off roll 8. Both take-off rollers 8, 9 are by the engine 43 and drive means 44 driven. The motor 43 is connected via the line 45 to a control device 30. The lower take-off roller 9 is fixedly connected to the machine frame (not shown), while the upper take-off roller 8 can be moved vertically in guides 13. The force required for the promotion of the material to be cut 10 in the direction of the arrow 15 is generated by a compression spring 12. The vertical position of the upper take-off roll 8 is detected by a connection 14 by a measuring device 11. The measuring device 11 is connected by a signal line 32 to the control device 30. The cut material 10, after it has left the feeding device 7 in the direction of the cutting device 17, is conveyed to the cutting table 18 of the cutting device 17 by a conveying means 42 (not shown in more detail but known per se). Thereafter, the pusher 3 moves back to its original position and is ready to deport the next material to be cut 10.
On the cutting table 18, the material to be cut 10 is positively positioned by means not shown here alignment in the longitudinal and transverse directions and then pressed by a punch 19 against the cutting table 18 and thus fixed. The ram 19 is disposed at the lower end of a spindle 20 which is drivingly connected to a servo motor 21 controlled by the servo drive 29 via the line 35. The servo drive 29 is connected via the signal line 34 to the sensor 22, which detects the position of the ram 19. By turning the spindle 20, the punch 19 is moved up or down. The servo drive 29 is connected to the control device 30 via the signal lines 36, 37. If the material to be cut 10 pressed on the cutting table 18 and thus fixed, this is then with a front knife 23 at the front and then cut with two side knives 24 on the head and on the foot. The order of cuts can also be reversed, head and foot before front trim. The front blade 23 moves vertically in the directions of the double arrow 25, while the two side blades 24 move in the directions of the double arrow 26 during the cutting operation. These directions of movement are in Fig. 1 indicated by the dashed lines 27 and 28. The cut material 10 is cut in a processing cycle. The guided blades 23 and 24 are driven by cranks 46, 47 via the linkages 48, 49. The cranks 46, 47 in turn are driven by the motor 50 to which they are connected via the drive means 51. The motor 50 is connected by the line 52 to the control device 30. It is obvious to choose the motors 43, 50 as servomotors. In this case, a servo drive is connected between the motors 43, 50 and the control device 30.
If the material to be cut 10 is cut and the pressure is released by lifting the ram 19, the material to be cut 10 is transported away from the cutting table 18 by means of a removal device, not shown.
The way transport device can be formed in a known manner as a slider, gripper or conveyor belt system. Preferably, a subsequent material to be cut 10 is conveyed simultaneously with the discharge of the cut material to be cut 10. To determine the machine angle M, a sensor 31 is provided, which is connected via a signal line 33 to the control device 30.
The individual processing steps thus include the feeding of the material to be cut 10 by pushing off the stacking device 4 and transferring the material to be cut 10 into the cutting device 17, the pressing of the material to be cut 10 on the cutting table 18 by means of press ram 19, the execution of the front section with the front blade 23 and the Seitenbeschnitt by the side knife 24 and the final release of the ram 19 from the cutting material 10th
These steps are in the Fig. 2 showing a processing cycle over the duration T, illustrated by the curves 38 to 41 and in dependence on the machine angle M.
The curve 38 shows the feeding of the material to be cut 10 from the stacking device 4 to the cutting table 18 between a machine angle of 130 ° to 260 ° on the transport path W. Shortly before the material to be cut 10 arrives in the cutting position on the cutting table 18, the ram 19 begins according to the curve 39 to reduce the pressing stroke D and reaches its lowest position on the cutting material 10 at about 300 °. The curve 40 shows the movement S _{F of} the front knife 23. This begins to lower at about 270 ° and begins shortly after the ram has reached its lower end position, with the cutting of a thick material to be cut 10 of thickness D _D , shortly after 300 ° , In the case of thin material to be cut with the thickness D _d , cutting begins, for example, about 30 ° later, at about 330 °. The lower end position of the front blade is reached at 0 °, from where the front blade 23 immediately after the return stroke to the upper end position begins. The movement of the side knives according to the curve 41 is analogous to the movement of the front knife, but in the present example phase-shifted by 110 °. This prevents a collision of the knives 23, 24. The total stroke S _{F of} the front blade 23 and S _{S of} the side knives 24 is always the same regardless of all other parameters.
Once the cutting is done by the side knife 24, the pressure is terminated according to curve 39 and the cut Material to be cut 10 is transported away from the cutting table 18. At the same time, the next item 10 to be cut is fed and the processing cycle just described is repeated. In the Fig. 2 curve 39a) for the course of the press corresponds to a pressing with the thickest and most bulky material to be cut 10. A less bulky material to be cut 10 results in a smaller stroke and a flatter course of the curve 39b). For a thin material to be cut 10 with the thickness D _d , the cutting process begins at about 333 °. Thus, additional time is available for the pressing process and the course of the pressing curve 39 becomes even flatter according to the course 39c). The time available when cutting a thin relative to a thick material to be cut 10 for the pressing process is now according to Fig. 2 from 0.21 T to 0.30 T substantially increased. Due to the longer pressing time, the air present in the material to be cut 10 can escape to a greater extent. This results in a much more stable stack due to a higher friction between the individual sheets. As already mentioned, this has a positive effect on the quality of the cut. The adaptation of the pressing movement to the different thickness D _D or D _{d of} the material to be cut 10 is merely an example here.
Alternatively, for example, the time gained for the extension of the alignment process or the transport of the cut material 10 may be used.
If the cutting operation with the front blade 23 and the side knives 24 is carried out at maximum speed under all operating conditions, this results in further advantages. This will be explained below with reference to Fig. 3 and Fig. 4 explained. If the cutter 1 according to the diagram in Fig. 3 operated at half speed, the cycle time Z is doubled to 2T. With rigidly coupled processes become so all times of the individual steps changed in proportion to the cycle time. The corresponding curves 38 ', 39', 40 'and 41' show the extension of the individual processing steps, for example, a longer transport time according to curve 38 '. Is according to Fig. 4 The speed of the cutting process is not halved accordingly, but is maintained for the cutting process the same time as in the diagram according to Fig. 2 needed, resp. 0.45 T. The proportion of the cutting process on one processing cycle is now reduced in favor of the remaining processing steps. Significantly more time is available for the remaining and quality-relevant processing steps. This additional time can be distributed to the other processing steps. In the diagram after Fig. 4 For example, the pressing time is 1.19 T versus 0.60 T with proportional distribution according to the diagram in Fig. 3 , With a material to be cut 10 with a comparatively large thickness D _{D still} results in a comparatively long pressing time of 1.11 T. Due to this significantly extended pressing time correspondingly much air can be pressed out of the material to be cut. Since the thickness of a cutting material 10 consisting of a plurality of printed products 5 can vary within a certain range, it is advantageous to know the effective relative thickness S _{R of} the material to be cut 10 before the pressing process, and thus optimally and continuously adjust the processing steps for each processing cycle to be able to. This is achieved on the basis of values previously determined in a calibration process and a continuous measurement of the thickness of the material to be cut 10 in the area of the feed device 7.

Calibration procedure:

First, the cutting device 1 on the dimensions of the printed products resp. be set of the cutting material.

• Relative Dickenmessung eines Schneidgutes 10 durch Messung der Distanz S_R der Abzugsrollen 8,9 mit der Messvorrichtung 11, bei der für den Abzugvorgang benötigten Kraft F_R und Abspeichern des Messwerts S_R(0) in der Steuervorrichtung 30, die zu diesem Zweck über die Signalleitung 32 mit der Messvorrichtung 11 verbunden ist.
• Fördern des Schneidgutes 10 auf den Schneidtisch 18, wobei der Pressstempel 19 sich in einer oberen Lage befindet.
• Absenken des Pressstempels 19 auf die Dicke D_L und Abspeichern des Messwertes D_L(0) in der Steuervorrichtung 30. Diese Dicke entspricht dem zugeführten Schneidgut 10, bevor die Luft ausgepresst ist. Bei dieser Dicke erfolgt die erste Berührung von Pressstempel 19 und Schneidgut 10. Die Erkennung dieser Position kann visuell durch den Bediener oder mittels optoelektronischen Sensoren erfolgen. Der Messwert der Position des Pressstempels 19 kann am Servoantrieb 29 abgefragt werden, der über die Signalleitung 34 mit dem Sensor 22 des Servomotors 21 verbunden ist.
• Aufbau der Presskraft F₂, die mindestens der in der Produktion benötigten Presskraft entsprechen soll und Messung der Dicke D₂(0)
• Aufbau der Presskraft F₁, die wesentlich kleiner als die Presskraft F2 sein soll und Messung der Dicke D₁ und Abspeichern des Messwerts D₁(0)

Under certain circumstances, even parts such as the cutting table 18 or the punch 19 must be replaced. The press die 19 is lowered to detect the 0-point on the cutting table 18 and the measuring system of the servo drive 29 calibrated. One in the diagram Fig. 5 held calibration process includes the following steps:

• Relative thickness measurement of a material to be cut 10 by measuring the distance S _{R of} the take-off rollers 8.9 with the measuring device 11, at the required force F _R for the withdrawal process and storing the measured value S _R (0) in the control device 30, for this purpose on the Signal line 32 is connected to the measuring device 11.
• Conveying the material to be cut 10 on the cutting table 18, wherein the pressing die 19 is in an upper position.
• Lowering of the ram 19 to the thickness D _L and storing the measured value D _L (0) in the control device 30. This thickness corresponds to the supplied cutting material 10 before the air is squeezed out. In this thickness, the first contact of the punch 19 and 10 cutting material takes place. The detection of this position can be done visually by the operator or by means of optoelectronic sensors. The measured value of the position of the press ram 19 can be interrogated on the servo drive 29, which is connected via the signal line 34 to the sensor 22 of the servomotor 21.
• Structure of the pressing force F ₂ , which should at least correspond to the pressing force required in production and measurement of the thickness D ₂ (0)
• Structure of the pressing force F ₁ , which should be much smaller than the pressing force F2 and measurement of the thickness D ₁ and storing the measured value D ₁ (0)

The construction of a certain force on the ram takes place via the construction of a corresponding torque on the servo motor 21 by the servo drive 29. With the help of points P ₁ (0) and P ₂ (0), the slope of the spring characteristic according to the formula C = (F ₂ - F ₁ ) / (D ₂ (0) - D ₁ (0)) and calculate the point P ₀ (0). The calibration process only has to be carried out on the first material to be cut 10, since the once-determined spring characteristic C can be regarded as constant, because the differences in the thickness S _R within a production are relatively small.
Assuming that in all printed products 5 of a series D ₀ -S _R , D _B and C of the material to be cut 10 are constant, depending on the currently measured thickness S _R (n), all other points, such as P ₀ (n) , P ₁ (n), P ₂ (n) and P _L (n).
The thickness D _{L of} a loose material to be cut 10 is calculated, for example, according to the formula: $${\mathrm{D}}_{\mathrm{L}}\left(\mathrm{n}\right)={\mathrm{<figure-callout\; id="0"\; label="D\; L"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">D\; </figure-callout>}}_{\mathrm{L}}\left(0\right)+\left({\mathrm{S}}_{\mathrm{R}}\left(\mathrm{n}\right)-{\mathrm{<figure-callout\; id="0"\; label="S\; R"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">S\; </figure-callout>}}_{\mathrm{R}}\left(0\right)\right)$$

The coordination of the drives is made by the control device 30, which is connected via the lines 37,45,52 with the drives or motors. The required measured values and signals are received by the control device 30 via the signal lines 32, 33, 36.
From the above explanations, it is obvious that by optimizing the pressing stroke, especially in the case of stiff and / or thin printed products 5, a substantial reduction of the pressing speed and above all of the acceleration can be achieved is. Regardless of the production speed, the cutting device 17 can always work at the maximum speed, which is not limited by the cutting speed, but by the limits determined by the mechanics. It is also essential that the cycle time Z, which is increased at low machine speeds, is available in particular for the transporting, aligning and pressing operations, since the cutting process always requires the same amount of time.

Claims (12)

1. Method for cutting several sides of a printed product (5, 10) over several processing steps of a processing cycle, with a cutting device (1), which has a stacking device (4) for taking printed products (5, 10), a feed device (7) for conveying the printed products (10) from the stacking device (4) into a cutting device (17) made with a press die (19) for pressing the printed products (10) onto a cutting table (18) and with knives (23, 24) for cutting the printed products (10) on the cutting table (18), in which the press die (19) and the knives (23, 24) are driven separately and their drives are controlled by a control device (30) and in which the processing cycle comprises at least the following processing steps:

   - feeding the printed products (10) from the stacking device (4) to the cutting device (17),

   - pressing the printed products (10) onto the cutting table (18) of the cutting device (17),

   - cutting the printed products (10) on the cutting table (18) of the cutting device (17),

   - releasing the press die from the cutting table (18) of the cutting device (17)

   and removing the cut printed products (10) from the cutting table, characterised in that a processing cycle, which is variable over time, made up of the processing steps of feeding, pressing, cutting and releasing, has a knife movement, which is constant over time, and feeding, pressing and releasing steps, which are variable over time, when cutting the printed products, and that the thickness of a material to be cut (10) consisting of several printed products (5) is determined using constant measurement of the thickness of the material to be cut.
2. Method according to claim 1, characterised in that the knife movements consist of a pre-stroke and a return stroke.
3. Method according to claim 1 or 2, characterised in that the values determined based on the bulkiness and/or spring characteristics (C) of the printed products (5) or the material to be cut (10) determine the upper end position of the stroke of the press die (19).
4. Method according to claim 3, characterised in that the thickness (D, d) of the material to be cut (10) is determined in the area of the feed device (2) by measuring.
5. Method according to claim 3 or 4, characterised in that the start of the pressure stroke is controlled depending on the thickness of the material to be cut (10), which has been determined.
6. Method according to one of claims 3 to 5, characterised in that the value required for a comparison of thickness is determined by a measuring device (11) on the material to be cut (10).
7. Method according to one of claims 3 to 6, characterised in that the spring characteristics (C) of the material to be cut (10) is determined by at least two pressing forces and the thicknesses measured from this.
8. Cutting device (1) for cutting several edges of a printed product (5, 10) in a processing cycle consisting of the processing steps of feeding, pressing and cutting the printed products (5, 10) as well as releasing the press die (19) from the printed products (10), which has a stacking device (4), a feed device (7), a press die (19) and a cutting device (17) consisting of several knives (23, 24) working together with this, in which the press die (19) and the knives (23, 24) of the cutting device (17) are driven separately and controlled by a control device (30), characterised by a measuring device (11) for constant determination of the thickness of a printed product (10) and a control device (30) connected to the measuring device (11) for time distribution between a cutting process, which is constant over time, and at least one of the rest of the processing steps of the processing cycle.
9. Device according to claim 8, characterised in that the cutting device (17) is made with a front knife (23) and two side knives (24) connected to this in a driven way.
10. Device according to claim 8 or 9, characterised in that the measuring device (11) is arranged in the area of the feed device (7).
11. Device according to claim 10, characterised in that the feed device (7) has its own drive device connected to the control device (30).
12. Cutting device according to one of claims 8 to 11, characterised in that the press die (19) is connected to a controlled servomotor (21) in a driven way.

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