Method and device for the in-register changing of delivery reels of preprinted webs supplied to the folding machine of a rotary printing press

Abstract

 A method for the in-register changing of delivery reels (1,3) of preprinted webs (B, B₁) supplied to the folding machine (2) of a rotary printing press consists of the rotation of the new reel (3) and of the direct monitoring of its peripheral speed to synchronise it with the speed of advance of the web (B) from the exhausted reel (1). Temporary variations of its speed of rotation are imparted to the new reel (3) until a print-starting reference (13) on the web (B₁) of the new reel (3) is in phase with corresponding references (14) provided on the web (B) of the exhausted reel (1). On completion of the phasing, the attachment of the web (B₁) of the new reel (3) to the web (B) which has run out is enabled.

Description

[0001] The present invention relates to the changing of motor-driven delivery reels of preprinted webs supplied to the folding machine of a rotary printing press, in which the web of a new reel must be joined in register to the web of an exhausted reel.

[0002] According to known techniques, in order to carry out these operations without the need to stop the printing press, magazines of festoons are conventionally needed, through which the web is supplied to the folding machine during the transition stage of replacement of the reel. The web of the new reel is joined in a stationary condition to the end of the festoon, and the new reel is rotated after this joint has been made.

[0003] These techniques are fairly complex, expensive and not very functional, particularly because of the need to use stacks of festoons.

[0004] The object of the present invention is to provide a method and a device for the rapid changing of the delivery reel, avoiding the need for magazines of festoons.

[0005] The method according to the invention is characterised essentially in that it comprises the steps of:
- rotating the new reel in the sense of unwinding of the web and directly monitoring its peripherial speed,
- comparing the peripheral velocity monitored with the speed of advance of the web of the exhausted reel and synchronising the speed of rotation of the new reel with this speed of advance by means of this comparison,
- detecting a print-starting reference on the web of the new reel and corresponding references on the web of the exhausted reel, and measuring the phase difference between these references,
- imparting temporary variations to the speed of variation of the new reel in response to this measurement, until the references are in phase,
- after phasing, enabling the attachment of the web of the new reel to the web which has run out.

[0006] In order to enable correct matching of the web of the new reel with a web printed by the press and supplied to the folding machine, the method according to the invention also comprises the steps of phasing the web of the new reel with the printed web by means of stretching and compensation.

[0007] The device for carrying out the method according to the invention is characterised in that it comprises:
- first speed-monitoring means directly associated with the periphery of the new reel and adapted to generate signals indicative of the peripheral speed thereof,
- second monitoring means adapted to generate signals indicative of the speed of advance of the web which has run out,
- comparator means supplied with the speed signals to determine the difference between the peripheral speed of the new reel and the speed of advance of the web which has run out, the comparator means being connected to the motor driving the new reel so as to synchronise the speed of rotation thereof with the speed of advance of the web which has run out, in dependence on the difference detected,
- a first print-starting reference applied to the periphery of the new reel and corresponding second references on the exhausted reel,
- first and second sensor means adapted to detect the first and second references respectively, and to generate corresponding detection signals,
- centering means supplied with the detection signals to determine the phase difference between the first and second references and adapted to send corresponding electrical signals to the comparator means by means of which temporary variations in its speed of rotation are imparted to the reel until the references are in phase, and
- control means piloted by the comparator means to enable, after phasing, the attachment of the web of the new reel to the web which has run out.

[0008] The device also conveniently includes a stretching unit and a compensating unit for checking the phasing of the web of the new reel with a web supplied by the printing press to the folding machine.

[0009] The invention will now be described in detail with reference to the appended drawing, provided purely by way of non-limiting example, which shows, in diagrammatic form, a device according to the invention for the in-register changing of delivery reels for preprinted webs supplied to the folding machine of a rotary printing press.

[0010] With reference to the drawing, a delivery reel for a preprinted web B supplied to a folding machine of known type, generally indicated 2, of a rotary printing press is indicated 1. The reel 1 is provided, also in known manner, with a motor-drive system comprising a continuous belt in entrainment contact with the periphery of the reel and an axial motor, not illustrated.

[0011] A second delivery reel for a new preprinted web is indicated 3 and, in the manner which will be made clear below, is intended to be substituted for the reel 1 when the latter is exhausted, to maintain the supply to the folding machine 2 without interrupting its continuity. The reels 1 and 3 are carried in known manner by a common rotatable support, not illustrated.

[0012] The reel 3 is provided with a motor-drive system including a continuous belt 4 (the same one as drives the reel 1) in tangential entrainment contact with the periphery of the reel and driven by means of a separately supplied direct-current electric motor 5, as well as an axial electric motor, not illustrated.

[0013] A first speed monitor, indicated 6, is constituted by an encoder directly associated with the periphery of the reel 3. The encoder 6 is adapted to generate electrical signals indicative of the peripheral speed of the reel 3 and to send such signals to an electronic control unit 7 including a comparator circuit. The electrical signals generated by a second speed monitor 8, also constituted by an encoder adapted to monitor the speed of advance of the web B which has run out and to generate corresponding electrical signals, are also sent to this comparator circuit. The speed of advance may be measured directly on the web B or, more conveniently, as in the embodiment illustrated, by monitoring the speed of the printing press associated with the folding machine 2. In this case, the encoder 8 is operatively associated with the drive of the press, schematically indicated 9, and the electrical signals generated thereby are subjected to a correction in dependence on the sizes of the printing cylinders operating from time to time, by means of a selector 10, before reaching the comparator circuit of the unit 7.

[0014] The comparator circuit of the unit 7 is connected, through a voltage regulator 11 and a four-quadrant rectifier 12, to the supply of the motor 5 of the belt 4 driving the reel 3.

[0015] As will become clear from the following, the encoders 6 and 8, with the comparator circuit of the unit 7, the regulator 11, the rectifier 12 and the motor 5, constitute a phase-control device for synchronising the speed of rotation of the reel 3 with the speed of advance of the web B which has run out.

[0016] A reference 13, constituted, for example, by an element of reflective aluminium or similar material stuck to the reel, is applied to the periphery of the reel 3 in exact correspondence with the starting point of the printing on the web forming the reel. Corresponding print-starting references 14, constituted, for example, by marks printed each half-length and spaced at a distance which is a multiple of the length, are arranged on the web B which has run out. A first photocell detector 15 and a second photocell detector 16 cooperate operatively with the reference 13 and the references 14, and are adapted to send corresponding electrical reference pulses to a centering circuit 17. This circuit 17 is arranged to measure the difference between the pulses received, corrected by a circuit 18 for checking the diameter of the reel 3 supplied by an axial encoder 19 associated with this reel, and to send corresponding signals to the comparator circuit of the unit 7. The latter operates the motor 5 driving the belt 4 through the voltage regulator 11 and the rectifier 12, in dependence on the difference between the pulses measured, in the manner specified below.

[0017] A sticking and cutting device of known type, not represented in the drawing, for the attachment by gluing of the new web to the web B which has run out, is associated with the region of tangential connection between the web B which has run out and that wound on the reel 3. This device is operated through an actuation circuit 20 piloted by the unit 7.

[0018] The cycle of the in-register changing of the reels 1 and 3 will now be described, starting from the condition, schematically illustrated in the drawing, in which the web B wound on the reel 1 is about to run out completely and the reel 3 is positioned tangentially to the web B in correspondence with the zone of the sticking device. At this stage, the drive of the exhausted reel 1 is transferred from its belt to the axial motor, while the new reel is driven to rotate in the sense of unwinding of the new web by means of its belt 4 which is driven by the motor 5. The encoder 6 is simultaneously brought alongside the periphery of the reel 3, and the sequence of synchronisation and in-register changing then starts. By means of the comparison between the signals coming to the encoder 6 and those coming from the encoder 8, the peripheral speed of the reel 3 is compared with the speed of advance of the web B by means of the comparator circuit of the unit 7 which pilots the motor 5 through the regulator 11 and the rectifier 12, until the two speeds are synchronised.

[0019] When the synchronised speed is about to be reached, the centering circuit 17 comes into operation and calculates the difference between the pulses transmitted by the photocell 15 upon the passage of the reference 13 on the reel 3 (the pulses being corrected in dependence on the diameter of this reel by means of the circuit 18) and those sent by the photocell 16 upon the passage of the references 14. In dependence on the difference detected, the comparator circuit of the unit 7 imparts temporary variations in the speed of rotation to the reel 3, through the regulator 11, the rectifier 12 and the motor 5, until the difference measured is less than a predetermined value which corresponds in practice to the phasing of the references 13 and 14.

[0020] At this point, the unit 7 enables, through the actuation circuit 20, the operation of the sticking and cutting unit which joins the web of the reel 3 to the exhausted reel B.

[0021] At this point, the new web, indicated B₁ on the right-hand side of the drawing, moves towards the folding machine 2 where a printed web B₂ coming directly from the printing press is supplied. In order to ensure correct matching between the web B₁ and the web B₂, the phasing of the web B₁ is controlled downstream of the sychronisation and phasing system described above. The web B₁ passes across a conventional type of load cell 21 which checks its winding drag and reaches a stretching unit 22 including motor-driven drag rollers 23 driven by autonomous motors 24, or, alternatively, driven by the drive 9 of the printing press with the possible use of a differential device of the "harmonic drive" type. The phasing of the web B₁ is then completed by means of a roller compensator unit 25 interposed between the stretching unit 22 and the folding machine 2.

Claims

1. A method for changing the motor-driven delivery reels of preprinted webs supplied to the folding machine of a rotary printing press, in which the web of a new reel must be joined in-register to the web of an exhausted reel, characterised in that it comprises the steps of:
- rotating the new reel (3) in the sense of unwinding of the web (B₁) and directly monitoring its peripheral speed,
- comparing the peripheral speed monitored with the speed of advance of the web (B) of the exhausted reel (1) and synchronising the speed of rotation of the new reel (3) with the speed of advance by means of this comparison,
- detecting a print-starting reference (13) on the web (B₁) of the new reel (3) and corresponding references (14) on the web (B) of the exhausted reel (1), and measuring the phase difference between these references (13, 14),
- imparting temporary variations to the speed of rotation of the new reel (3) in response to this measurement, until the references (13, 14) are in phase, and
- after phasing, enabling the attachment of the web (B₁) of the new reel (3) to the web (B) which has run out.

2. A method according to Claim 1, in which the web (B₁) of the new reel (3) is intended to be combined at the folding machine (2) with a printed web (B₂), characterised in that it further includes the steps of phasing the web (B₁) of the new reel (3) with the printed web (B₂) by means of stretching and compensation.

3. A method according to Claim 1 or Claim 2, characterised in that the speed of advance of the web (B) which has run out is monitored as the printing speed of the printing press.

4. A device for the changing of motor-driven delivery reels of preprinted webs supplied to the folding machine of a rotary printing press, in which the web of a new reel must be joined in-register with the web of an exhausted reel, characterised in that it comprises:
- first speed-monitoring means (6) directly associated with the periphery of the new reel (3) and adapted to generate signals indicative of the peripheral speed thereof,
- second speed-monitoring means (8) adapted to generate signals indicative of the speed of advance of the exhausted web (B),
- comparator means (7) supplied with the speed signals to determine the difference between the peripheral speed of the new reel (3) and the speed of advance of the web (B) which has run out, the comparator means being connected to the motor driving the new reel (3) so as to synchronise the speed of rotation thereof with the speed of advance of the web (B) which has run out, in dependence on the difference detected,
- a first print-starting reference (13) applied to the periphery of the new reel (3) and corresponding second references (14) on the web (B) which has run out,
- first and second sensor means (15,16) adapted to detect the first (13) and second (14) references respectively and to generate corresponding detection signals,
- centering means (17) supplied with the detection signals to determine the phase difference between the first (13) and second (14) references and adapted to send corresponding electrical signals to the comparator means (7) by means of which temporary variations in its speed of rotation are imparted to the new reel (3) until the references (13, 14) are in phase, and
- control means (20) piloted by the comparator means (7) to enable, after phasing, the attachment of the web (B₁) of the new reel (3) to the web (B) which has run out.

5. A device according to Claim 4, characterised in that the first and second speed-monitoring means comprise two encoders (6,8) of which the first is operatively associated with the periphery of the new reel (3) and the second is associated with the drive (9) of the printing press.

6. A device according to Claim 4, characterised in that the first and second sensor means are constituted by photocells (15, 16).

7. A device according to any one of Claims 4 to 6, in which the web (B₁) of the new reel (3) is intended to be matched with a printed web (B) supplied to the folding machine (2), characterised in that it further includes a stretching unit (22) and a compensating unit (25) for checking that the web (B₁) of the new reel (3) is in phase with the printed web (B₂).

Drawing