GB2093810A - Label cutting and collecting apparatus - Google Patents

Abstract

Apparatus for cutting and collecting sheets comprises means for feeding a continuous web (W) to a rotary cutter (C) operable to make repeated cuts across said web to separate successive lengths thereof as discrete sheets, and a delivery unit (D) for receiving said sheets and collecting them in a stack (55, 56) in which separate electric motors (M1; M2; M3; M4) are provided for driving at least one web feed device (F2), the cutter (C), and the delivery unit (D), with electronic control means (93) arranged to control the speeds of said motors in response to a common speed control signal and means (95) for sensing marks on said web, said sensing means being connected to said electronic control means to influence the speed control of at least one of said motors to control the speed of the cutter relative to the web speed so that the cuts across said web are made at predetermined positions relative to said marks. <IMAGE>

Description

SPECIFICATION Label cutting and collecting apparatus This invention relates to apparatus for cutting and collecting sheets (e.g. labels) or like articles, produced by printing or otherwise marking successive lengths of a continuous web (usually a paper web), said apparatus being required to cut the web to separate said lengths as discrete sheets and stack the sheets in groups each containing a desired number. More particularly the invention is concerned with drive equipment for such apparatus.

In such apparatus the drive equipment is required to move the web at an accuratelydetermined speed to a cutter, to operate the cutter at regular intervals so that successive pieces severed from the web are of uniform length, and to drive a transfer device receiving the severed sheets and feeding them to a stack. The apparatus may be "on-line" i.e. coupled to a printing or like machine by which the web is supplied, or may be "off-line", i.e. a separate unit arranged to draw web from a reel.

According to the present invention there is provided apparatus for cutting and collecting sheets or like articles, comprising means for feeding a continuous web to a rotary cutter operable to make repeated cuts across said web to separate successive lengths thereof as discrete sheets, and a delivery unit for receiving said sheets and collecting them in a stack in which separate electric motors are provided for driving at least one web feed device, the cutter, and the delivery unit, with electronic control means arranged to control the speeds of said motors in response to a common speed control signal and means for sensing marks on said web, said sensing means being connected to said electronic control means to influence the speed control of at least one of said motors to control the speed of the cutter relative to the web speed so that the cuts across said web are made at predetermined positions relative to said marks.

Preferably the sensing means and electronic control means are so arranged that the speed of the cutter and of the delivery unit are varied whenever the sensing means emits a signal indicating that the position of cut is becoming incorrect relative to the marks on the web.

Preferably also said electronic control means is connected to a microprocessor wherein the latter may set the control means to maintain the motor speeds at suitable values for a desired sheet length, having regard to the circumference of a knife drum in the rotary cutter and the circumference of feed rolls in the web feeding means. The cutter may be a changeable unit, so that when an alteration of sheet length is required the unit may be changed for one with a knife drum circumference which is related to the new sheet length. Alternatively said electronic control means may be arranged to set the speed of the knife drum so that the knife speed and the web speed are in synchronism when the longest length of sheet is being cut.Said electronic control means may be arranged to increase the speed of the knife drum relative to that of the web when a shorter length of sheet is required to be cut so that the cuts take place at the correct position along the web.

To assist a full understanding of the invention, a preferred embodiment thereof will now be described, by way of example only, reference being made to the accompanying drawings in which: Figure 1 is a diagrammatic side view of a label cutting and collecting mechine in which a web is drawn from a reel; Figure 2 is a block diagram of control circuits for drive motors used in the machine of Fig. 1; Figure 3 is a view similar to Figure 1 but showing a modified form of machine; Figure 4 is a diagrammatic side view of an alternative form of delivery unit for use in the machine of Figures 1 , and Figure 5 is a diagrammatic side view of part of a label cutting and collecting machine in which a web is supplied from a printing machine.

Figure 1 illustrates diagrammatically an "offline" machine in which a continuous web W of printed sheets is drawn from a supply reel R through a pair of feed rolls F1, a lateral register device L, a further pair of feed rolls F2, and longitudinal slitters S to a transverse cutter unit C.

Successive sheets cut from the web by said cutter pass into a deliery unit D.

In passing from the reel R to the feed rolls F1, the web W passes around a loop formed by a movable guide roller 10 between the feed rolls F1 and a fixed guide roller 1 the movable roller 10 changes its position when there is any change in the tension of the web W leaving the reel R, and such movement of the roller 10 is used in known manner to control a brake associated with the reel R to stabilise the web tension produced by the first pair of feed rolls F1 which draw the web from the reel R. After passing the rolls F1 the web goes round a second loop formed by a movable guide roller 20, between a fixed guide roller 21 and the feed rolls F1. The movement of the guide roller 20 is also used for web tension control as will be described below.

The cutter unit C includes a lower knife drum 40, having a number of knife blades 40A equispaced around its periphery, and an upper anvil roller 41. The delivery unit D includes a pickoff roller 41 A which carries sheets from the roller 41 to a transfer roller 50 around the periphery of which are positioned a reject roller 51 and two delivery rollers 52, 53. The rollers 41, 41 A, 50, 51 52 and 53 are all suction rollers (i.e. in their peripheral surfaces they have ports connected by internal passages, and, through their mountings, to a suction device, not shown) so that they can retain on their surfaces the sheets produced by the cutter C; each roller being positioned so that a sheet is transferred from one roller to the next by appropriate control of the suction in each roller.

The roller 51 and rollers 52, 53 are selectively connected to the suction device, so that a sheet carried on the surface of the roller 50 is removed when it reaches whichever one of the rollers 51, 52, 53 is at that moment so connected. The roller 51 is thus operative when it is desired to reject a sheet, and serves when operative to deliver the sheet to a reject box 54 while the rollers 52, 53 are operative aiternatively, each for a sufficient time to deliver a desired number of sheets to an associated collecting device 55 or 56 in which the received sheets are collected in a stack.

The roller 50 has suction apertures disposed in lines on its peripherai surface, each line of apertures being parallel to the rotational axis of the roller and the circumferential spacing between successive lines is such that when a sheet transfers from the roller 41 A to the transfer roller 50, it is required that a line of suction apertures on the roller 50 should be presented to the sheet close to its leading edge, to ensure efficient transfer to the roller 50 and to keep the leading edge of the sheet against the surface of the roller 50 as the latter revolves. The speed and phasing of the rollers 41 A, 50 is so controlled that one line of apertures reaches the position at which a sheet is transferred respectively from rollers 41 and 41 A as a sheet arrives there.

It will be noted that four separate drive motors are provided; motor M1 for the cutting unit C; motor M2 for the delivery unit D; motor M3 for the feed rollers F2 and a motor M4 for the feed rollers F1.

Turning now additionally to Figure 2, here is shown in diagrammatic form the control circuits for the four motors M1, M2, M3, M4. Each of said motors has a closed-loop speed control, in which, respectively, a shaft sensor 71, 72, 73, 74 delivers an electric signal to one input X of a comparator unit 81, 82, 83, 84; a second input Y of each comparator unit receives a control signal. The sensors 71, 72, 73 are digital encoders while the sensor 74 is a tacho-generator, as the control loop for the motor M4 operators on analogue voltages, while the control loops for the other three motors operate on digital signals.In alternative arrangements the sensor 71 is mounted either on the shaft of the cutter drum 40, instead of the motor M1. as shown in chain-dot lines in Figure 2 or, on the shaft of the anvil roller 41.

A main control input Z receives a master control signal (in digital form) representing the required speed of operation of the apparatus, and this signal is modified according to different parameters before being applied to the Y input of each of the comparator units 81,82,83 and 84.

In the case of the motor M4, driving the feed rolls F1, said master control signal is applied to the Y input of comparator unit 84 via a digital to analogue converter 90 and any convenient type of positional transducer, such as a rotary potentiometer 91. The guide roller 20, is carried on one end of a lever 100 (Figure 1), the other end being pivoted at 101. The potentiometer 91 is mounted on the pivot so that movement of the roller 20 causes rotation of the potentiometer 91.

The resulting signal modifies the control signal applied to the Y input of the comparator unit 84 in the sense to stabilise the tension in the web W.

The master control signal is modified by two units before application to the Y input of comparator unit 83 to control the motor M3 driving the feed rolls F2. Firstly, said master control signal is applied to a unit 92, which is controlled by a microprocessor 93. Secondly, the modified control signal delivered by the unit 92 is applied to one input A of a control gate 94, the other input B of the gate 94 being connected to a register mark sensor system 95 of any convenient type, which senses marks applied to the web W in register with the printing thereon.

The modified control signal delivered by the unit 92 is also applied to the Y input of comparator unit 81 to control the motor M1 driving the cutting unit C, and, through a control gate 96 to the Y input of comparator unit 82 controlling the motor M2 driving the delivery unit D. The gate 96 and the comparator unit 81 for motor M1 are each also controlled by the microprocessor 93.

In operation, the master control signal, which is in a digital frequency form, is compared in the unit 83 with a signal derived from the sensor 73, delivering a control signal to motor M3 in a sense to cancel any inequality by increasing or decreasing the motor speed to bring said speed to a desired value. The unit 92 modifies the master control signal under control of the microprocessor 93, gate 94 further modifies the control signal when the sensor 95 reports any register error, so that the speed of motor M3 changes until the register error disappears.

The unit 81 is controlled by the microprocessor 93 to regulate the speed of motor M1 (and hence of cutting unit C) to produce the required sheet length, and gate 96 is also controlled by the microprocessor so that the speed of the delivery unit D is matched to the sheet length as well as the speeds of the other parts of the apparatus.

One factor which is fed into the microprocessor 93 is the sheet length, and the speed control of motor M2 is modified by the gate 96, under microprocessor control, to set the speed of roller 50 so that a line of suction apertures meets each sheet close to its leading edge.

A modified form of machine will now be described with reference to Figure 3, in which the same reference numerals as used in Figure 1 are used for like parts. As the construction and operation of the machine of Figure 3 are substantially the same as the machine of Figure 1, only the differences will be described.

Instead of being mounted on the lever 100 (Figure 1) the guide roller 20 is connected to an endless chain 60 which extends between sprockets 61, 62. Movement of the roller 20, due to changes of tension in the web W, ca-uses rotation of the chain 60 which, in turn, causes rotation of the potentiometer 91. As with the machine of Figure 1, the resulting signal modifies the control signal applied to the Y input of the comparator unit 84. In the cutter unit of Figure 3 the knife drum 40 is positioned above the anvil roller 41, instead of below, as in Figure 1. This means that the directions of rotation of the drum 40 and roller 41 are reversed, relative to that of the same drums when positioned as in Figure 1.In consequence the sheets are transferred directly from roller 41 to the transfer roller 50 (the direction of rotation of which is the same as in the machine of Figure 1), without having to use a pickoff roller, such as shown at 41 A in Figure 1.

In an alternative, and simplified, form of delivery unit, as shown in Figure 4, a suction delivery roller 1 52 is positioned adjacent the anvil roller 41. With this arrangement cut sheets produced by the knives 40A are picked up directly from the anvil roller 41 by the roller 1 52 and delivered to an associated collecting device 1 56 in which the received sheets are collected in a stack.

To allow for ease of access to the cutter unit C for maintenance and, when necessary, to change the cutter unit C for one which produces sheets of a different size, the delivery unit D is mounted on wheels 105 (Figures 1 and 3) so that it may readily be moved away from the cutter unit C.

In an alternative form of cutter unit C the microprocessor 93 is arranged to set the speed of the motor M1, and thus the speed of the knife drum 40, so that the knife speed and the speed of the web W are in synchronism when the longest length of sheet is being cut. When a shorter length is required to be cut the knife speed is increased relative to that of the web so that the cuts take place at the correct position along the web.

The apparatus of the invention may also be used in an "on-line" condition, and this will be described with added reference to Figure 5 in which like parts bear the same reference numeral as in Figure 1.

The web W of printed sheets is supplied by a printing machine PM and passes round a loop formed by the movable guide roller 20, between the roller 21 and a further fixed roller 21A. The web then passes, as described above, through the lateral register device L, the feed rolls F2, slitters S and transverse cutter unit C, into the delivery unit D. In this case the motor M4, comparator unit 84, converter 90 and potentiometer 91 are not required as the feed rolls corresponding to the feed rolls F1 in Figure 1, and the associated tension control system, form part of the machine PM and are not shown in Figure 5.

The master control signal applied to the input Z is derived from the printing cylinder (not shown) of the machine PM. This signal is then modified, before being applied to the motors M1, M2, M3 as described above with reference to Figures 1 and 2.

Claims (7)

1. Apparatus for cutting and collecting sheets or like articles, comprising means for feeding a continuous web to a rotary cutter operable to make repeated cuts across said web to separate successive lengths thereof as discrete sheets, and a delivery unit for receiving said sheets and collecting them in a stack in which separate electric motors are provided for driving at least one web feed device, the cutter, and the delivery unit, with electronic control means arranged to control the speeds of said motors in response to a common speed control signal and means for sensing marks on said web, said sensing means being connected to said electronic control means to influence the speed control of at least one of said motors to control the speed of the cutter relative to the web speed so that the cuts across said web are made at predetermined positions relative to said marks.

2. Apparatus as claimed in claim 1 in which the sensing means and electronic control means are so arranged that the speed of the cutter and of the delivery unit are varied whenever the sensing means emits a signal indicating that the position of cut is becoming incorrect relative to the marks on the web.

3. Apparatus as claimed in claim 1 or claim 2 in which said electronic control means is connected to a microprocessor wherein the latter sets the control means to maintain the motor speeds at suitable values for a desired sheet length, having regard to the circumference of a knife drum in the rotary cutter and the circumference of feed rolls in the web feeding means.

4. Apparatus as claimed in any of the preceding claims in which said cutter is a changeable unit, so that when an alteration of sheet length is required the unit may be changed for one with a knife drum circumference which is related to the new sheet length.

5. Apparatus as claimed in claim 3 in which said electronic control means is arranged to set the speed of said knife drum so that the knife speed and the web speed are in synchronism when the longest length of sheet is being cut.

6. Apparatus as claimed in claim 5 in which said electronic control means is arranged to increase the speed of the knife drum relative to that of the web when a shorter length of sheet is required to be cut so that the cuts take place at the correct position along the web.

7. Apparatus for cutting and collecting sheets or like articles substantially as described herein with reference to the accompanying drawings.