Transverse sheet withdrawal brake

Abstract

A method for operating a device that applies a force to a print sheet during a folding operation, wherein the print sheet is in a specified starting position prior to the folding operation. Braking-force triggering pulses are directed toward the print sheet to counter the acceleration of the print sheet in the starting phase of the folding operation and/or to counter fluttering movements that occur during the intake of the print sheet. The pulses exert an intermittent, uniform or oscillating force onto at least a section of the print sheet. The pulses are controlled by a control unit which operates based on control profiles resulting from queried operating parameters and/or based on stored control profiles.

Claims

1. A device for making available braking forces that act upon a print sheet during a folding operation, wherein the print sheet is in a specified starting position prior to the folding operation, comprising: a transverse sheet brake operable during a folding operation to generate braking-force triggering one or more pulses that cause intermittent, uniform or oscillating braking forces that act upon at least a section of the print sheet to counter an acceleration of the print sheet that occurs in a starting phase of the folding operation and/or to counter fluttering movements of the print sheet that form during an intake of the print sheet into the folding operation; and a control unit to control the braking-force triggering pulses which is operated based on changeable control profiles resulting from queried operating parameters of production data including at least one of a folding pattern, paper weight, paper width and cut-off length and/or by stored control profiles relating to at least one of said parameters.

2. A method for operating the device according to claim 1 to make available braking forces acting upon a print sheet during a folding operation, wherein the print sheet is in a specified position before reaching the folding operation, comprising: directing braking-force triggering pulses, that are triggered by the transverse sheet brake toward the print sheet to counter at least one of acceleration of the print sheet that occurs during a starting phase of the folding operation and fluttering movements that form during the intake of the print sheet to the folding operation, wherein the pulses are triggered to act intermittently, uniformly or oscillatingly on at least a section of the print sheet; and controlling the braking-force triggering pulses by the control unit operated with the at least one of changeable control profiles resulting from queried operating parameters and the stored control profiles.

3. The method according to claim 2, including generating the braking-force triggering pulses pneumatically.

4. The method according to claim 2, including transmitting at least one of the intermittent, uniform or oscillating braking-force pulses to the print sheet directly, semi-directly or indirectly.

5. The method according to claim 2, including triggering the braking force pulses mechanically, electronically, hydraulically or pneumatically, and focusing the braking force pulses directly or indirectly onto the print sheet.

6. The method according to claim 2, wherein the braking-force triggering pulses act upon the print sheet to generate an increase in friction between the print sheet and a table support surface.

7. The device according to claim 1, wherein the transverse sheet brake is operative to directly, semi-directly or indirectly transfer the intermittent, uniform or oscillating braking forces to the print sheet.

8. The device according claim 1, further including a table support surface for the print sheet, and the transverse sheet brake is operative to generate braking-force triggering pulses to act upon the print sheet to cause an increase in friction between the print sheet and the table support surface.

9. The device according to claim 1, wherein the transverse sheet brake is operative to supplement at least one braking force acting upon the print sheet during the intake of the print sheet to the folding operation with an additional braking force which acts upon the back edge of the print sheet or is effective in a region of the back edge.

10. A device for making available a braking force that acts upon a print sheet along a feeding direction to a folding operation and during the folding operation, wherein a print sheet is in a specified starting position prior to a folding operation, comprising: a braking force generating means operative to generate braking force triggering pulses effective along a feeding direction for the print sheet, applied directly or indirectly to the print sheet to exert intermittent, uniform or oscillating braking forces onto the print sheet, while the print sheet is in an operative connection with the folding operation, to position the print sheet in the specified starting position for the folding operation, wherein the braking force triggering pulses are at least one of pneumatic, mechanical and vacuum generated to cause friction to the print sheet; a transverse sheet brake operative to generate during the folding operation braking-force triggering pulses that cause intermittent, uniform or oscillating braking forces that act upon at least a section of the print sheet to counter an acceleration of the print sheet that occurs in a starting phase of the folding operation and/or to counter fluttering movements of the print sheet during an intake of the print sheet into the folding operation; and a control unit to control all the braking-force triggering pulses, the control unit being operated based on at least one of changeable control profiles resulting from queried operating parameters of production data including at least one of a folding pattern, paper weight, paper width and cut-off length and/or by stored control profiles relating to at least one of said parameters.

11. A method for operating a device according to claim 10 to apply braking-forces to the print sheet along the feeding direction to the folding operation and during a folding operation, comprising: generating pneumatic, mechanical or vacuum generated braking-force triggering pulses that are effective along the feeding direction of the print sheet, and applying the braking-force generated triggering pulse directly or indirectly to the print sheet to exert the intermittent, uniform or oscillating braking-forces to the print sheet to position the print sheet in the specified starting position for the folding operation; and while the print sheet is subjected to the folding operation, generating braking-force triggering pulses by the transverse sheet brake for causing intermittent, uniform or oscillating braking forces to act on the print sheet to at least one of counter an acceleration of the print sheet that occurs during a starting phase of the folding operation and counter fluttering movements of the print sheet during the folding operation; and controlling the braking-force triggering pulses by the control unit during the intake of the print sheet which is operated based on the at least one of changeable control profiles resulting from queried operating parameters and the stored control profiles.

12. A method of using the device according to claim 10, for braking and positioning a print sheet in a feeding direction and for delaying the print sheet during an intake for a folding operation and/or to counter flattering movements that occur during print sheet intake, the method comprising: computing an air pressure needed for braking based on a specified production data including at least one of a folding pattern, paper weight, paper width and cut-off length, and sending an information regarding the computed pressure to an automatic pressure controller, taking into consideration the print sheet has different values on the left and right side based on a folding pattern; computing the air pressure required for slowing down the print sheet during intake into the folding station and/or to counter the flattering movements based on specified production data including at least one of the folding pattern, paper weight, paper width and cut-off length, and sending an information regarding the computed air pressure to an automatic pressure controller, taking into consideration that the left and right side of the print sheet have different values, depending on the folding pattern for the print sheet; filling a pressure reservoir located in front of a pneumatic switching valve in the flow direction with the computed pressure; detecting the print sheet entering or fed into a folding region by a light barrier along the back edge of the print sheet, wherein the light barrier simultaneously serves to ensure a synchronizing of a folding sword with a precise clock speed, and the light barrier detects irregularities within the belt transport of the print sheet and compensates for the irregularities with the control unit; triggering a signal for activating a pneumatic switching valve based on an activated trigger signal, taking into consideration a dead time and speed compensation; following the triggering, releasing abruptly the air stored in the pressure reservoir to cause an air nozzle to release a pulse-type air blast; transmitting the released air blast directly onto the print sheet or indirectly to a lever, which transmits a force of the air blast and the corresponding normal force onto the print sheet; pressing the print sheet during the feeding operation and/or during the folding process onto a table-type support and generating a braking force for the print sheet as a result of friction; exerting simultaneously or with a phase delay an additional braking force onto the back edge of the print sheet, wherein a material stretching results from the braking operation to cause stiffening of the print sheet; selecting the stopping instant such that the print sheet is braked securely to 0, or fits uniformly against the sheet end stop, or the folding sword takes over the print sheet or it is delayed during the folding process; and following release of the air pulses, closing the pneumatic switching valve immediately and filling the air reservoir again by the pressure controller with air to a predetermined pressure level to make air available for a following cycle.

13. The device according to claim 10, wherein the transverse sheet brake is operative to directly, semi-directly or indirectly transfer the intermittent, uniform or oscillating braking forces to the print sheet.

14. The device according to claim 10, wherein the brake-force generating means includes mechanical, electronic, hydraulic or pneumatic means to generate the braking forces which are focused directly or indirectly onto the print sheet.

15. The device according claim 10, further including a table support surface for the print sheet, and wherein the brake-force generating means is operative to generate braking-force triggering pulses to act upon the print sheet to cause an increase in friction between the print sheet and the table support surface.

16. The device according to claim 15, wherein the brake-force generating means generates a vacuum which acts in a feeding direction of the print sheet to the folding operation and upon an underside of the print sheet to increase a friction between the underside of the print sheet and the table support surface.

17. The device according to claim 10, wherein the brake-force generating means includes means to supplement at least one braking force acting upon the print sheet during an intake of the print sheet to the folding operation with an additional braking force which acts upon a back edge of the print sheet or is effective in a region of the back edge.

18. The device according to claim 10, wherein the brake-force generating means includes means to generate and apply at least one braking force in connection with forming an overlapping flow or separating sheets from an overlapping flow in a feeding direction of the transported print sheets.

19. The device according to claim 10, wherein the brake-force generating means generates at least one pneumatically driven braking force and further including at least one switching valve having a nozzle to control the at least one pneumatically driven braking force as a function of a feeding speed and texture of the print sheet.

20. The method according to claim 11, wherein the braking-force triggering pulses are generated pneumatically.

21. The method according to claim 11, including transmitting at least one of the intermittent, uniform or oscillating braking-force pulses to the print sheet directly, semi-directly or indirectly.

22. The method according to claim 11, including triggering the braking force pulses mechanically, electronically, hydraulically or pneumatically, and focusing the braking force pulses directly or indirectly onto the print sheet.

23. The method according to claim 11, wherein the braking-force triggering pulses act upon the print sheet to generate an increase in friction between the print sheet and a table support surface.

24. The method according to claim 11, including generating a vacuum which acts upon an underside of the print sheet to increase friction on the print sheet in the feeding direction.

25. The method according to claim 11, including supplementing at least one of the braking forces acting upon the print sheet during the feeding of the print sheet with an additional braking force which acts upon a back edge or back edge region of the print sheet.

26. The method according to claim 11, including using at least one braking force to form an overlapping flow of the print sheets transported in the feeding direction or separating sheets out of an overlapping flow.

27. The method according to claim 11, including controlling at least one pneumatic braking force with at least one nozzle of a switching valve, taking into consideration at least one of a feeding speed and a texture of the print sheet.

28. A device for making available braking forces that act upon a print sheet along a feeding direction to a folding operation and during the folding operation, wherein the print sheet is in a specified starting position prior to the folding operation, comprising: a braking force generating means operative to generate braking force triggering pulses effective along a feeding direction for the print sheet, applied directly or indirectly to the print sheet to exert intermittent, uniform or oscillating braking forces onto the print sheet, while the print sheet is in an operative connection with the folding operation, to position the print sheet in the specified starting position for the folding operation, wherein the braking force generating means comprises at least one of a vacuum generator to generate a vacuum acting upon the print sheet and at least one mechanical element, to bring the print sheet to a standstill at the specified starting position; a transverse sheet brake operative to generate during the folding operation braking-force triggering pulses that cause intermittent, uniform or oscillating braking forces that act upon at least a section of the print sheet to counter an acceleration of the print sheet that occurs in a starting phase of the folding operation and/or to counter fluttering movements of the print sheet during an intake of the print sheet into the folding operation; and a control unit to control all the braking-force triggering pulses, the control unit being operated based on at least one of changeable control profiles resulting from queried operating parameters of production data including at least one of a folding pattern, paper weight, paper width and cut-off length and/or by stored control profiles relating to at least one of said parameters.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is explained in the following with further detail and with reference to the drawing, to which we expressly refer for all details not emphasized further in the description. All elements not absolutely necessary for the direct understanding of the invention were omitted. The same elements in different figures are provided with the same reference numbers,

(2) The drawing shows in:

(3) FIG. 1 is a perspective schematic showing a complete overview of a longitudinal folding device, including a transport belt for supplying print sheets according to an embodiment of the invention.

(4) FIG. 2 shows an enlarged area of FIG. 1 with a modification including an intermediary mechanical element used for braking and positioning of the print sheet in connection with applying an air pulse as the braking force according to another embodiment of the invention.

(5) FIG. 3 shows an enlarged area of FIG. 2 and further including geometric conditions and resulting forces during a braking operation.

(6) FIG. 4 is a perspective view of a transverse sheet brake that can be activated by air pulses.

(7) FIG. 5 an end view of a portion of FIG. 4 showing the operational mode of the transverse sheet brake in connection with the intake of the print sheet for the folding operation.

(8) FIG. 6 is a diagram of the course of the folding operation, in a view crosswise to the intake direction of the print sheet.

(9) FIG. 7 is a diagram of the course of the folding operation in a position where the print sheet is taken over by the folding rollers.

(10) FIG. 8 is a diagram of the course of the folding operation in a position where the transverse sheet brake is activated.

(11) FIG. 9 is a diagram of the course of the folding operation in a position where the transverse sheet brake is deactivated.

DETAILED DESCRIPTION OF THE INVENTION

(12) FIG. 1 shows the area surrounding a longitudinal folding device 100, which essentially includes a longitudinal folding device 101 which can be operated using a folding sword 102. FIG. 1 also shows the configuration of the folding roller pair 103. The operation of the longitudinal folding device 101 is illustrated with a print sheet 104 which is folded in a longitudinal direction. Of course, the print sheet can also be folded inside a cross-folding device, not shown further herein, wherein this device is operatively connected to the shown longitudinal folding device 101 or can be operated as an autonomous unit. A print sheet 105 is supplied via transport belts 106 and is stopped in the precise folding position 107, wherein the table-type support is not shown in further detail. For a better understanding reference is made to FIG. 6 which illustrates the table-type support 106a. FIG. 1 furthermore shows a trailing print sheet 108, designed to illustrate a clocked operation in the longitudinal folding device 100.

(13) The operative connection between such a longitudinal folding device and a precise positioning of the print sheet 105 takes place as follows:

(14) Based on the specified production data such as folding pattern, paper weight, paper width and cut-off length, the air pressure needed for the braking is computed and the information sent by a control unit 119 to the automatic controller, taking into consideration that depending on the folding pattern, the print sheet has different values on the left and on the right side.

(15) Furthermore, based on the specified production data such as folding pattern, paper weight, paper width and cut-off length, the air pressure required for the braking is computed for decelerating the print sheet 105 for the intake into the folding device and this information is sent by the control unit 119 to the automatic pressure controller 109, taking into consideration that the print sheet may have different values for the left and the right side, depending on the folding pattern.

(16) The illustrated air nozzle 110 is used to blow the air directly onto the print sheet. It is simultaneously taken into consideration that an additional amount of air may be necessary to neutralize the possibly occurring fluttering movements, following the intake of the print sheet 105. Of course, in that case it should also be considered that even after a complete stop of the print sheet 105, an additional introduction of air may be required for stabilizing the print sheet 105.

(17) Thus, the pressure reservoir 111, arranged in the flow direction in front of a pneumatic switching valve, is filled with the pressure controller 109 to the required pressure level.

(18) The print sheet 105 entering/fed into the folding region is detected at the back edge with the aid of a light barrier, not shown in further detail here, wherein this light barrier simultaneously functions to precisely synchronize the clock speed of the folding sword 102, wherein the operation of the light barrier also detects irregularities within the belt transport of the print sheet 105 and compensates these via the control unit 119.

(19) As a result of an activated trigger signal, a signal for activating the pneumatic switching valve is triggered, taking into consideration the dead time and speed compensation.

(20) Following this, the air stored in the pressure reservoir 111 is released abruptly, whereupon the air nozzle 110 releases a pulse-type stream of air that acts upon the print sheet 105.

(21) The released air blast can act directly upon the print sheet 105, or upon a lever (see FIG. 2, Position 112) which transmits the air blast and the corresponding normal force to the print sheet. Of course, a configuration is also conceivable for which the air blast acts upon the print sheet 105 as well as the lever 112, wherein the direct and indirect braking-force introduction can also be controlled by the control unit 119 to be intermittent and with differing pulse strengths of the air pulses (see FIG. 2, Position 114).

(22) During the feeding operation and/or during the folding process, the print sheet 105 is pressed by the triggered pneumatic forces onto the table-type support 106a and generates a braking force for the print sheet as a result of friction.

(23) If necessary, an additional braking force can be directed simultaneously or phase-displaced onto the back edge of the print sheet 105, wherein the material stretching triggered by the braking effect results in a stiffening of the print sheet 105.

(24) The braking instant (see FIG. 3, Position 115) is selected such that the print sheet 105 is securely slowed to 0 and, in an imaginary sense, also when using a print sheet end stop, as described in the above. This specification can also be met if the slowing down of the print sheet 105 to 0 has reached the imaginary stopping point (FIG. 3, Position 113) where the folding sword 102 takes over the print sheet as intended. The takeover of the print sheet 105 by the folding sword 102 can thus be coordinated such that it coincides with the imaginary stopping point 113 of the print sheet end.

(25) One option for a precisely positioned braking of the print sheet 105, which is not shown further, can be achieved by activating an additional braking force based on friction. This can advantageously be achieved through generating a vacuum that acts upon the underside of the print sheet, wherein this option can without problem also be used together with the other previously explained braking forces. FIG. 2 shows furthermore the folding position 116 of the print sheet 105.

(26) FIG. 3 shows the geometric conditions and the forces resulting therefrom during the course of decelerating the print sheet. These values, namely the distances 230 and 240, as well as the forces F.sub.pulse 200, F.sub.braking 210 and F.sub.normal 220, which occur during the braking operation, are of a qualitative nature and are used as basis for a controlled braking operation, wherein a parameterizing of these values for a control/regulation of the braking operation is also possible.

(27) Following the release of the air pulses (FIG. 2, Position 114), the pneumatic switching valve is closed immediately and the pressure controller 109 fills the compressed air reservoir 111 again with air to the predetermined pressure level, thus making it available for the next cycle.

(28) FIG. 4 shows a transverse sheet brake 117, which can be activated with several air pulses 114, effective in the end region of the print sheet. For that purpose, the transverse sheet brake 117 is operatively connected to a pipe 118, arranged above this position, which is admitted with air stored in the pressure reservoir (see FIG. 1, Position 111). This transverse sheet brake 117 is capable of stopping the print sheet individually to achieve a precise position and, in addition, to effect a delay to counter strong intake forces and to furthermore start a neutralizing to counter possibly occurring fluttering movements during the folding operation. It is advantageous if this transverse sheet brake 117 that acts upon the print sheet is operated autonomously. If necessary it could be combined with a delay stemming from the vacuum.

(29) FIG. 5 shows the sequence of steps within the longitudinal folding device 100, relative to the introduced air pulses 200 and the vector direction of the delay forces and/or the braking forces V.sub.braking 210 and/or the normal force F.sub.normal 220 that develops on the conveying belt.

(30) FIG. 6 shows a schematic course of the folding operation carried out by the longitudinal folding device 100, in a view that is transverse to the intake direction of the print sheet 105, arranged on the table-type support 106a. FIG. 6 shows the position occupied by the print sheet 105 before the rollers 103 of the folding device (see also FIG. 1) engage. As can be seen, the pneumatically triggered transverse sheet brakes 117 are effective on both sides of the folding sword 102 (see also FIG. 7), wherein the location and number of transverse sheet brakes shown herein are only of a qualitative nature. The starting point for using the transverse sheet brake 117 directly depends on the start of the intake of the print sheet 105, but need not occur simultaneously. The position 250 characterizes the speed of the folding rollers 103

(31) FIG. 7 shows the schematic sequence of the folding operation at a position where the print sheet 105 is taken over by the folding rollers 103. As can be seen, the pneumatic transverse sheet brakes 117 are effective on both sides of the folding sword 102, wherein the location and number of transverse sheet brakes shown herein are only of a qualitative nature. The operational starting point for the transverse sheet brake 117 therefore is connected to the start of the intake of the print sheet, but must not occur at the same time. In most cases, the transverse sheet brake is first activated at the start of the folding operation. The pulse strength emitted by the transverse sheet brake essentially depends on the initial intake speed V.sub.sheet (down arrow; see also FIG. 8 or 9; Position 290) of the print sheet 105 which is a product of a.sub.accelerationt.sub.time 270, wherein it also depends on whether additional braking forces are provided and purposely applied. The speed V.sub.sheet 290 of the drawn-in print sheet 105 is equal to the speed of the roller V.sub.roller. The position 280 illustrates the end of the print sheet 105. The speed of the folding sword 102 is illustrated by the arrow arranged above and pointing downward (without position number).

(32) FIG. 8 shows the schematic course of the folding operation in a position where the transverse sheet brake 117 is activated by the illustrated air pulses 114. As can be seen, the pneumatic transverse sheet brakes 117 are effective on both sides of the folding sword 102 (see FIG. 7), wherein the herein shown locations and the number of transverse sheet brakes are of a qualitative nature. The starting point for using the transverse sheet brake 117 depends on the start of the intake of the print sheet 105, but need not occur simultaneously. The pulse strength exerted by the transverse sheet brake essentially depends on the intake speed V.sub.sheet 290 of the print sheet 105, which is characterized as V.sub.sheet=V.sub.roller. The speed of the drawn-in print sheet V.sub.sheet is therefore equal to the speed of the roller V.sub.roller. No acceleration takes place during this operation, in contrast to the conditions shown in FIG. 7.

(33) FIG. 9 shows the schematic course of the folding operation in a position where the transverse sheet brake 117 is deactivated. According to a preferred embodiment, the transverse sheet brake 117 is deactivated approximately 10 mm before the end of the print sheet intake 310, so that the transverse sheet brake 117 if possible remains active during the complete operation and to ensure that no air below affects the edge of the print sheet during the end phase of the intake, which could cause a damaging lifting up of the edge of the print sheet 105.

(34) The invention has been described in detail with respect to exemplary embodiments, and it will now be apparent from the foregoing to those skilled in the art, that changes and modifications may be made without departing from the invention in its broader aspects, and the invention, therefore, as defined in the appended claims, is intended to cover all such changes and modifications that fall within the true spirit of the invention.