GB1580056A - Slow-down on sheeting machines - Google Patents

Description

(54) SLOW-DOWN ON SHEETING MACHINES (71) We, DRG(UK) LIMITED, of 1 Redcliffe Street, Bristol, BS99 7QY, a British Company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to sheeting machines, and more particularly to means for slowing the rate of travel of sheets between the cutter and the delivery end of such a machine.

In a conventional sheeting machine, a web of sheet material is unwound from a reel, if necessary it is slit longitudinally to form narrower webs, and it is then cut transversely by a rotary cutter into unit sheet lengths. After that, the individual sheets are conveyed in succession by endless conveying tapes moving at a slightly higher speed than the cutter so as to produce a space between successive sheets, and thence to a slow-down unit where the sheets encounter a slower moving endless conveyor so that they close up on each other and overlap each other to an appreciable extent. The sheets are thus conveyed to the delivery station in the form of a shingled stream. At the delivery end there is a socalled layboy, which comprises an elevator table carrying a removable pallet for the stack of sheets. The shingled stream of sheets is fed onto this pallet, the individual sheets being arrested by a backstop so that they form a vertical stack on the pallet.

This conventional arrangement is satisfactory for moderate paper speeds, but at higher paper speeds now contemplated, a conventional slow-down conveyor will not slow the sheets sufficiently and satisfactorily, so that the speed of arrival at the delivery station will be too high. The final arrest of the sheets at their leading edge is therefore too abrupt, thus causing buckling of the sheets owing to their relatively high momentum.

According to the present invention there is provided a sheeting machine having a cutting station and a delivery station and a path between the cutting and delivery stations, the path comprising a slow-down conveyor having endless conveyor means for the paper arranged to travel at a speed less than that of the speed of the sheet through the cutting station, and a preliminary slow-down unit located before the slow-down conveyor, the preliminary slow-down unit comprising a rotor arranged to engage the surface of each sheet in passing during a part only of each revolution, the rotor being driven through a transmission arranged to give a cyclicly varying angular velocity to the rotor, the rotor being arranged to engage each sheet during a period when its angular velocity is decreasing, whereby the speed of travel of the sheet is correspondingly decreased during said period of engagementm Preferably the rotor is adjustable so that its peripheral speed at the moment of initial engagement with the sheet can be matched with or brought to a desired proximity to the speed of travel of the sheet. Conveniently, the sheet engaging portion of the rotor is angularly adjustable with respect to the cyclic drive to the rotor, whereby the particular part of the drive cycle during which the rotor engages the sheet can be selected. The rotor conveniently comprises separate leading and trailing sheet engaging portions each angularly adjustable with respect to the cyclic drive to the rotor, whereby the leading portion can be set to a part of the cyclic drive such as its peripheral speed matches or approximates to that of the sheet on initial engagement, and the trailing portion can be set to a part of the cyclic drive such that its peripheral speed at the point of breaking engagement is the desired slowed speed of the sheet. Preferably the leading and trailing portions overlap in the circumferential direction whereby unbroken contact with the sheet is maintained between initial engage ment by the leading portion and breaking engagement by the trailing portion. The drive to the rotor is preferably adjustably linked to the earlier cutting and conveying drive of the sheeting machine so that the engagement of the rotor with each sheet can be selected so as to extend wholly or principally over the trailing half of the sheet. By this means, the sheet is, in effect, slowed down from the rear rather than from the front as in existing arrangements, and consequently a controlled rate of deceleration can be effected without buckling of the sheets.

In order that the invention may be more clearly understood, one embodiment will now be described with reference to the drawings accompanying the Provisional Specification wherein: Fig. 1 shows a diagrammatic side view of the sheeting machine incorporating the invention.

Fig. 2 shows an end view of part of the preliminary slow-down mechanism, and Fig. 3 shows diagrammatically a crosssectional view on the line III-III of Fig. 2.

Referring to the drawings, and firstly to Fig. 1; a continuous web of sheet material is drawn from a suitable unwind module, if necessary via a longitudinal slitting module, and fed to a cutting module 12 at which the web is cut transversely into unit sheet lengths by any suitable mechanism, such as a rotary knife 14 co-operating with an anvil 16, and driven by motor 18. From the cutting module 12 the sheets pass onto a slightly faster moving endless conveyor 20 comprising one or more parallel endless tapes passing around end rollers, at least one of which is driven from the motor 18 to provide the conveying action. If desired, an upper endless tape conveyor 22 can be provided to contact the upper surfaces of the sheets during this section. Because the lower tapes are travelling faster than the initial speed of the web, the sheets are somewhat spaced apart over this section. The first tape conveyor 20 passes the sheets over a deflector module 24 which is arranged to deflect any desired sheet into a secondary path where it is delivered for example to a slow down conveyor and layboy, being a duplicate of the arrangement described below, or to a reject station 26.

This deflector module can be omitted if desired. The rest of the sheets pass over the deflector module to a nip between slowdown rollers 44, 46, which will be described in more detail later. Individual sheets are slowed thereby as their trailing end portions pass between the rollers. so that they are delivered at a considerably slower speed to a slow-down conveyor 36. The conveyor 36 may likewise comprise a number of parallel endless conveyor tapes, including conven tional check rolls 37 to check the sheets at their leading edge and bring them to the conveyor speed. The conveyor is driven at a speed suitable for delivery of the sheets to the layboy 48 where they are arrested by a backstop 50 and fall to form a stack on a pallet located on an elevator table 52. If desired, particularly in the case of sheets which are particularly difficult to handle, the upper endless conveyor 22 can be extended over this slow-down region, to act as an upper guide for the sheets, although because of its higher speed it should not form a nip with the lower conveyor. A separate upper guide belt, travelling at the same speed as conveyor 36, could be provided instead, although it will still not provide a nip with the conveyor 36, except perhaps at the check roll position. Other upper guide means, such as fixed guide bars, could alternatively be provided. The sheets which are slowed down by the preliminary slow-down rollers 44, 46 are thereby caused to close up on each other and are formed in a shingled fashion on the slow-down conveyor 36. The check rolls 37 further close the sheets up on each other before delivery to the layboy. Instead of or in addition to the check rolls 37, the tails of the sheets could be checked just after the slowdown mechanism 44, 46, by conventional means such as suction or intermittent tail nip rolls.

The slow-down rollers 44, 46 are shown in more detail in Figs. 2 and 3. The lower roller 46 is of uniformly cylindrical form carried in journals 54. Each journal 54 is pivoted at 56 eccentrically of the axis of rotation of the roller 46 to a fixed side member 58 of the machine framework. On the opposite side of the roller axis the journal is mounted to the frame member 58 to an adjustable link 60, whereby the axis of the roller 46 can be adjusted with respect to that of the roller 44.

The roller 44 comprises a shaft 62 which is journalled at its ends directly to the opposite frame members 58, and carries at intervals along its length pairs of rotor members 64,66 respectively. Each rotor member is secured on the shaft 62 by means of clamps 68. At the periphery of the rotor member there are raised regions 70, 72 respectively which effectively increase the diameter of the rotor member over a region of its periphery. The position of the lower roller 46 is adjusted so that it is in sheet-nipping relationship with the raised portions 70, 72 of the rotor members, but does not engage the rotor members over the rest of their periphery. The regions 70, 72 are preferably of resilient material such as rubber, to reduce the risk of marking the sheets. This resilience also makes the setting of the spacing of the axes of the rollers 44, 46 less critical, and may even enable the adjustment device 60 to be dispensed with.

The resilience could additionally or alternatively be provided in the surface of the roller 46. The two rotor members of each pair are arranged so that their raised portions 70, 72 overlap each other, as shown in Figs. 2 and 3.

Thus, with respect to the direction or rotation of their upper rollers 44, the raised portion 72 will first engage a sheet passing through the nip, and will be referred to as the leading sheet engaging portion, while the raised portion 70 which engages the sheet last will be referred to as the trailing sheet engaging portion. The leading edge 74 of the leading sheet engaging portion 72 defines the point of initial sheet engagement, while the trailing edge 76 of the trailing sheet engaging portion 70 defines the point of breaking engagement with the sheet. Between these two points, the sheet is continuously nipped under one or both of the raised portions 70, 72. The length of the nip can therefore be readily adjusted by selecting the required overlap between the raised portions when clamping the rotor members to the shaft.

The lower roller 46 may be freely rotatable, and not driven except by engagement with the upper roller. Alternatively, the lower roller 46 may be driven by direct gear engagement from the upper roller shaft 62, for example by meshing gears 61, 63. The upper roller is driven through a pair of elliptical gears 78, 80, respectively. The gear 78 is carried on one end of the shaft 62, while the meshing gear 80 is journalled to the adjacent frame member 58, and carries a flywheel 82, and a bevel gear 84 through which the drive is taken from a uniformly rotating source, suitably derived from the motor 18. The drive connection may be by means of toothed belts or chains, or by means of bevel gears through a shaft extending lengthwise of the machine, the drive being interrupted by a clutch. The timing of the periodic nipping of the sheets by the slow-down rollers can be accurately linked to the cutting and subsequent conveying of the sheet lengths simply by decoupling the clutch and altering the angular relationship between each part of the longitudinally extending shaft and the knife drive. The upper gear 78 is adjustably sec ured to the shaft 62 by end screws 96; the gear being wedged onto a frusto-conical por tion 98 of the shaft. Between the head of the screw 96 and the gear 78 there is an annular disc 100, aligned to the shaft 62 and carrying a pointer 102. On the face 104 of the gear 78 under the pointer 102 there is marked a scale (not shown) by means of which the angular relationship of the shaft 62 to the gear 78 can be accurately set. Elliptical gears are a well known device for providing a cyclicly varying angular velocity in a driven shaft from a uniformly moving drive. For a wider range of varying angular velocity, more than one pair of elliptical gears may be employed in con secutive arrangement. There are other such mechanisms, such as a four-bar link or a slider crank mechanism, or electrical or hydraulic drives which could be used in the present invention if desired.

In the initial setting up of the slow-down mechanisms before a run, various factors have to be taken into consideration. Firstly, there is the speed at which the sheets arrive at the preliminary slow-down mechanism, and the speed at which it is desired the sheets should be delivered to the layboy. Then there is the unit length of each sheet to be considered, and the synchronising of the preliminary slow-down mechanism with respect to the sheet conveyor so that each sheet arrives at the periphery of the slow-down mechanism at the correct moment during rotation of the upper roller 44. The arrival of each sheet is determined by the sheet conveyor system, but the slowed speed of the sheet as delivered from the preliminary slow-down mechanism is determined by the speed of rotation of the upper roller 44 at the point of breaking contact with the sheet, that is to say when the trailing edge 76 is opposite the roller 46.

Possibly the simplest way of carrying out this adjustment is to have one of each pair of rotor members, for example the members 66, fixed in angular relationship with the shaft 62 so that by altering the angular relationship between the shaft 62 and gear 78, the speed of the leading edge 74 of the rotor members 66 at the point of initial engagement (as shown in Fig. 3) can be preset, using the pointer 102 on the scale. The scale can conveniently be calibrated in equivalent circumferential length per revolution. The other rotor member 64 of each pair can then be adjusted to give the correct length of nip so that the trailing edge 76 arrives opposite the roller 46 at the desired slower speed. This could easily be calibrated relative to sheet length. Having thus set the upper roller 44 so that the initial and final engagement speeds are correct, it is then necessary to synchronise the slow-down rollers with the rest of the sheet conveyor system so that the nip takes place over the desired region of the sheet. It is particularly preferred that the nip should take place over the trailing half of the sheet, so that the sheet is in effect slowed down from the rear. By this means, buckling of the sheet should be prevented, even at high rates of deceleration. This synchronisation is simply effected by means of the clutch in the drive transmission, and conveniently the adjustment is made so that the point of breaking engagement substantially coincides with the trailing edge of the sheet passing through the nip.

A notable feature of the present invention is that controlled decleration can be achieved, since the sheet is being slowed from the rear. In addition, a conventional slow-down conveyor with leading edge check rolls leading to a layboy can be used, while the preliminary slow-down mechanism enables a much higher speed of the web through the cutting zone. By way of example; if the delivery to the layboy from the slowdown conveyor should be at 30 metres/min., and the slow-down conveyor can receive sheets at 120 metres/min., the preliminary slow-down mechanism may slow the sheets to that speed from as much as 300 metres/min. These figures do not of course indicate limits of speed in using this invention.

WHAT WE CLAIM IS: 1. A sheeting machine having a cutting station and a delivery station and a path between the cutting and delivery stations, the path comprising a slow-down conveyor having endless conveyor means for the paper arranged to travel at a speed less than that of the speed of the sheet through the cutting station, and a preliminary slow-down unit located before the slow-down conveyor, the preliminary slow-down unit comprising a rotor arranged to engage the surface of each sheet in passing during a part only of each revolution, the rotor being driven through a transmission arranged to give a cyclicly varying angular velocity to the rotor, the rotor being arranged to engage each sheet during a period when its angular velocity is decreasing, whereby the speed of travel of the sheet is correspondingly decreased during said period of engagement.

2. A sheeting machine according to claim 1 wherein the rotor is adjustable so that its peripheral speed at the moment of initial engagement with the sheet can be matched with or brought to a desired proximity to the speed of travel of the sheet.

3. A sheeting machine according to claim 2 wherein the sheet engaging portion of the rotor is angularly adjustable with respect to the cyclic drive to the rotor, whereby the particular part of the drive cycle during which the rotor engages the sheet can be selected.

4. A sheeting machine according to claim 3 wherein the rotor comprises separate leading and trailing sheet engaging portions each angularly adjustable with respect to the cyclic drive to the rotor, whereby the leading portion can be set to a part of the cyclic drive such as its peripheral speed matches or approximates to that of the sheet on initial engagement, and the trailing portion can be set to a part of the cyclic drive such that its peripheral speed at the point of breaking engagement is the desired slowed speed of the sheet.

5. A sheeting machine according to claim 4 wherein the leading and trailing portions overlap in the circumferential direction whereby unbroken contact with the sheet is maintained between initial engagement by the leading portion and breaking engagement by the trailing portion.

6. A sheeting machine according to any one of the preceding claims wherein the drive to the rotor is adjustably linked to the earlier cutting and conveying drive of the sheeting machine so that the engagement of the rotor with each sheet can be selected so as to extend wholly or principally over ths trailing half of the sheet.

7. A sheeting machine according to any one of the preceding claims wherein the sheet engaging portion of the rotor or of a co-operating component forming a nip therewith or both is made of resilient material so as to accommodate differing thicknesses of sheet material.

8. A sheeting machine substantially as described herein with reference to the drawings accompanying the Provisional Specification.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. enables a much higher speed of the web through the cutting zone. By way of example; if the delivery to the layboy from the slowdown conveyor should be at 30 metres/min., and the slow-down conveyor can receive sheets at 120 metres/min., the preliminary slow-down mechanism may slow the sheets to that speed from as much as 300 metres/min. These figures do not of course indicate limits of speed in using this invention. WHAT WE CLAIM IS:

1. A sheeting machine having a cutting station and a delivery station and a path between the cutting and delivery stations, the path comprising a slow-down conveyor having endless conveyor means for the paper arranged to travel at a speed less than that of the speed of the sheet through the cutting station, and a preliminary slow-down unit located before the slow-down conveyor, the preliminary slow-down unit comprising a rotor arranged to engage the surface of each sheet in passing during a part only of each revolution, the rotor being driven through a transmission arranged to give a cyclicly varying angular velocity to the rotor, the rotor being arranged to engage each sheet during a period when its angular velocity is decreasing, whereby the speed of travel of the sheet is correspondingly decreased during said period of engagement.

2. A sheeting machine according to claim 1 wherein the rotor is adjustable so that its peripheral speed at the moment of initial engagement with the sheet can be matched with or brought to a desired proximity to the speed of travel of the sheet.

3. A sheeting machine according to claim 2 wherein the sheet engaging portion of the rotor is angularly adjustable with respect to the cyclic drive to the rotor, whereby the particular part of the drive cycle during which the rotor engages the sheet can be selected.

4. A sheeting machine according to claim 3 wherein the rotor comprises separate leading and trailing sheet engaging portions each angularly adjustable with respect to the cyclic drive to the rotor, whereby the leading portion can be set to a part of the cyclic drive such as its peripheral speed matches or approximates to that of the sheet on initial engagement, and the trailing portion can be set to a part of the cyclic drive such that its peripheral speed at the point of breaking engagement is the desired slowed speed of the sheet.

5. A sheeting machine according to claim 4 wherein the leading and trailing portions overlap in the circumferential direction whereby unbroken contact with the sheet is maintained between initial engagement by the leading portion and breaking engagement by the trailing portion.

6. A sheeting machine according to any one of the preceding claims wherein the drive to the rotor is adjustably linked to the earlier cutting and conveying drive of the sheeting machine so that the engagement of the rotor with each sheet can be selected so as to extend wholly or principally over ths trailing half of the sheet.

7. A sheeting machine according to any one of the preceding claims wherein the sheet engaging portion of the rotor or of a co-operating component forming a nip therewith or both is made of resilient material so as to accommodate differing thicknesses of sheet material.

8. A sheeting machine substantially as described herein with reference to the drawings accompanying the Provisional Specification.