GB2275885A

GB2275885A - Longitudinal cutting device for webs

Info

Publication number: GB2275885A
Application number: GB9404776A
Authority: GB
Inventors: Georg Riescher; To Hoang Minh; Wilhelm Eberle
Original assignee: MAN Roland Druckmaschinen AG
Current assignee: Manroland AG
Priority date: 1993-03-13
Filing date: 1994-03-11
Publication date: 1994-09-14
Anticipated expiration: 2014-03-11
Also published as: GB2275885B; CH687302A5; GB9404776D0; DE4308044C1

Description

2275885 Longitudinal Cutting Device for Webs This invention relates to a

longitudinal cutting device for webs, and is concerned with such a device which includes a driven circular blade which extends into a cutting groove in a cutting roller.

It is known to longitudinally cut webs by means of a so-called bursting cut using an apparatus comprising a circular blade and a cutting roller having a circumferential cutting groove into which the circular blade projects. Rollers co-operating with the cylindrical surface of the cutting roller on both sides of the cutting groove clamp the web firmly as it is cut. These rollers can be combined with an intermediately-lying cutting blade to form a so-called blade roller. In the case where the apparatus is to be used in a web processing operation in which there is to be no longitudinal cut, the blade roller is exchanged for a clamping roller. When set against the cutting roller it functions as a feed roller for non-slip web transport.

When making the bursting cut, it is advantageous if the circular blade is driven with a phase lead i.e. so that its circumferential speed is greater than the web speed. For this purpose it is known to drive the circular blade at an appropriate speed by means of an electric motor. This is expensive and is complicated in its construction.

D-AS 12 22 784 describes a drive for two blade mandrels which carry circular blades. For the purpose of adjustability of the degree of overlap of the circular blades, the blade shafts are eccentrically mounted. Even after eccentric adjustment the driving pinions of the blade shafts engage with internally- toothed drive wheels.

It is an object of the present invention to provide a longitudinal cutting device with a means of driving the circular blade which is of simple construction.

Accordingly, the present invention provides a cutting device for longitudinally cutting a web, which device comprises:

(i) a circular blade for projecting into a circumferential cutting groove in a cutting roller over which the web passes, (ii) a clamping roller to hold the web against the cutting roller adjacent the cutting groove, and (iii) a drive connecting the clamping roller and the circular blade so that the circular blade is rotated by rotation of the clamping roller.

Thus, a separate electric motor to drive the circular blade is not necessary. Furthermore the device can be of simple construction. The device can therefore be produced cost-effectively.

In a particularly preferred embodiment, the clamping roller drives the circular blade with a phase lead.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:- Fig. 1 is an axial section through one embodiment of a longitudinal cutting device in accordance with the present invention, Fig. 2 is an axial section through another embodiment of a longitudinal cutting device in accordance with the present invention, Fig. 3 is a section, similar to that of Figure 2, in respect of a third embodiment in accordance with t- he invention, and 35 Fig. 4 is a longitudinal section through the longitudinal cutting device of Fig. 2.

Referring now to Fig. 1, the longitudinal cutting device includes a circular blade 1 having a shaft located in a bore in a boss of a clamping roller 2 so that the blade is mounted for rotation about an axis coaxial with the axis of rotation of clamping roller 2. The shaft of the circular blade 1 carries a spur gear wheel 4 and a spur gear wheel 3 is carried by the boss of the clamping roller 2. The spur gear wheels 3 and 4 are in engagement with pinions 5 and 6 respectively on an intermediate shaft 7 which is mounted in a clamping roller lever 8. The clamping roller lever 8 is pivotally mounted in machine frame 9.

By means of a drive (not shown), for instance a pneumatic or hydraulic working cylinder, the clamping roller lever 8 together with the circular blade 1 and the clamping roller 2 can be set onto a cutting roller 10. In the set state the peripheral surface of the clamping roller 2 cooperates with the cylindrical surface of the cutting roller 10 to form a nip though which web 12 passes. Also, when in the set state, the circular blade 1 projects into a circumferential cutting groove 11 of the cutting roller 10. Thus in use the web 12, guided on the cutting roller 10, is cut in accordance with the bursting cut principle. The clamping roller 2 set onto the web 12 and pressing it against the cutting roller 10 ensures slip-free guiding of the web and clamping of the web transversely to its direction of travel. Furthermore, the clamping roller 2 is driven by the web 12 by friction. This rotary movement of the clamping roller 10 is transmitted to the circular blade 1 by means of the spur wheel 3, pinions 5 and 6 via the intermediate shaft 7, and the spur wheel 4. Because of the relative sizes of spur wheels 3 and 4 and pinions 5 and 6, the rotational speed of the circular blade 1 is greater than the rotational speed of the clamping roller 2, and thus the circumferential speed of the circular blade 1 1r is greater than the linear speed of the web 12. Thus there is a phase lead whereby a clean cut is obtained. In order to ensure non-slip driving of the clamping roller 2 by the web 12, it carries on its periphery a ring 13 of a material which has a high friction coefficient such as Vulcollan.

As an alternative to the gear drive for the circular blade as shown in Fig. 1, a belt drive can be used. In this case, the spur wheels and pinions will be replaced by pulleys.

Referring now to Fig. 2, the drive comprises a clamping roller 16 having a bearing shaft 15 held in a clamping roller lever 14. This clamping roller 16 is divided into two discs 17 and 18 mounted for rotation about the bearing shaft 15. The bearing shaft 15 has an eccentric middle section 19 (having eccentricity e) on which a circular blade 20 is mounted for rotation. The disc 17 carries a gear wheel 21 having internal teeth with which a pinion 22, connected to the circular blade 20, engages. Each disc 17 and 18 carries on its periphery a ring 23, 24 of friction material such as Vulcollan. On an end of the bearing shaft 15 there is secured a lever 25 whereby the shaft 15 can be angularly displaced about its axis. A working cylinder 26 (Fig. 4) having one end secured articulatedly to the clamping roller lever 14 engages,at its other end, with the lever 25. A further working cylinder 28 pivotally supported at one end on machine frame 27 is articulated to the clamping roller lever 14 at its other end (Fig. 4).

As in the case of Fig. 1, the lever 14, together with the clamping roller 16 and the circular blade 20, is set onto cutting roller 29 by means of the working cylinder 28 (Fig. 4). In this set position when the working cylinder 26 is suitably actuated to angularly -- ------_------------------ - displace shaft 15 such that the middle section 19 is in position A as shown in Fig. 4, the circular blade 20 projects into cutting groove 30 of the cutting roller 29 and makes a longitudinal cut in web 31. Because of 5 the relative sizes of the gear wheel 21 and the pinion 22, the circular blade 20 is driven, by the clamping roller 16, with a phase lead with respect to the clamping roller 16 and the web 31, thus producing a clean cut. The disc 17 carrying the gear wheel 21 is driven by friction from the web 31.

When the action of the working cylinder 26 is reversed, the eccentric middle section 19 of the bearing shaft 15 assumes the position A' whereby the circular blade 20 is withdrawn out of the cutting groove 30 and away from the web 31. In this position of the circular blade 20 there is therefore no longitudinal cutting and the device behaves only as a clamping roller. Switching between the cutting and clamping mode and the clamping only mode is very simple and may be carried out, for example, by a push button on a panel near the cutting device or by remote control from a control station. However, it can also take place automatically within a pre-set system. In any event, the manual changing of a circular blade for a clamping roller and vice versa, with the associated changing and assembling times (which have hitherto been necessary when the type of production was changed) are obviated. Furthermore the circular blade is protected between the discs of the clamping roller and there is therefore less danger of it being damaged.

It is also relatively easy to optimise the angle of intersection (cutting angle). The cutting relationships for the device according to Fig. 2 are shown in Fig. 4. A small cutting angle (angle of intersection) should be aimed for to produce a good cut. This is the case when the dipping point B of the circular blade 20 (i.e. the point where the blade enters the groove) is near the contact point C between the clamping roller 16 and the cutting roller 29. In order to achieve this the middle point of the circular blade when in adjustment position A seen in the running direction of the web has to be spaced as far as possible from the middle point of the clamping roller and the cutting roller. This can be achieved, for example, by adjusting the final position of the piston rod head of the working cylinder 26.

Fig. 3 shows a modification of the device of Fig.

2. Here the device includes a bearing shaft 33 which is held in a clamping roller lever 32 and has a bore 34 which is offset from the central axis of shaft 33 by eccentricity e. A circular blade 35 with its shaft 36 is mounted in this bore. Furthermore, first disc 37 of a two-part clamping roller 38 is mounted on the bearing shaft 33. Second disc 39 of the clamping roller 38, with its shaft 40, is mounted concentrically with the disc 37 in the clamping roller lever 32. This disc 39 carries an internal toothing 41 with which a pinion 42 secured on the shaft 36 engages. Rings 43 and 44 made of a friction material such as Vulcollan project from the discs 37 and 39 at their peripheries. A working cylinder 46 supported on the clamping roller lever 32 engages with a lever 45 on the bearing shaft 33. The clamping roller lever 32 is pivotally mounted in machine frame 47 and a working cylinder (not shown) similar to that of Fig. 2 pivots the clamping roller lever 32 together with the clamping roller 38 and the circular blade 35 towards and away from a cutting roller (not shown).

The circular blade 45 is driven by the disc 39 by means of its internal toothing 41 and the pinion 42.

The withdrawal of the circular blade 35 from the cutting roller groove is effected by rotation of the bearing shaft 33 by means of the working cylinder 46.

Otherwise the device fdnctions like the longitudinal cutting device of Fig. 2 and produces similar advantageous effects.

In the longitudinal cutting devices shown in Figs.

2 and 3, the circular blade is driven by means of gear wheels. However, if desired, the circular blade can be driven by means of a friction drive and this is also within the scope of the invention. In this case the circular blade may be firmly connected to a friction wheel which is in contact with a friction wheel having an appropriate internal surface on one of the discs of the clamping roller. Also within the scope of the invention is the case where the circular blade is driven, by the clamping roller, by means of planetary gears. For example, the clamping roller may include an internally toothed wheel meshing with planetary gears which are engaged with a sun wheel bonnected to the circular blade. Using planetary gears it is possible to drive a circular blade arranged concentrically with the clamping roller. Finally, in contrast to tAe illustration in Fig. 1, the cutting roller can be provided with a ring incorporating a cutting groove and support surfaces for the clamping roller only in the zones where cutting is to be effected (provided that the web is not looped around the cutting roller).

Claims

Claims:

v 1. A cutting device for longitudinally cutting a web, which device comprises:

(i) a circular blade for projecting into a circumferential cutting groove in a cutting roller over which the web passes, (11) a clamping roller to hold the web against the cutting roller adjacent the cutting groove, and (Iii) a drive connecting the clamping roller and the circular blade so that the circular blade is rotated by rotation of the clamping roller.
2. A device as claimed in claim 1, wherein the circular blade is mounted eccentrically with respect to a bearing shaft and means is provided to angularly displace the bearing shaft.
3. A device as claimed in claim 2 wherein said means comprises a working cylinder acting on a lever connected to the bearing shaft.
4. A device as claimed in claim 1, 2 or 3 wherein the drive is a gear drive.
5. A device as claimed in claim 4, wherein the drive comprises a gear wheel carried by the circular blade, a gear wheel carried by the clamping roller and an intermediate shaft having two pinions respectively engaging the gear wheels.
6. A device as claimed in claim 4, wherein the drive comprises a gear wheel on the clamping roller and having internal toothing in engagement with a pinion rotating with the circular blade.
7. A device as claimed in claim 4 wherein the drive comprises planetary gears.
8. A device as claimed in claim 1, 2 or 3 wherein the drive is a belt drive.
9. A device as claimed in claim 1, 2 or 3 wherein the drive is a friction drive.
10. A device as claimed in any one of the preceding claims, wherein the periphery of the clamping roller includes material having a high coefficient of friction.
11. A device as claimed in any one of the preceding claims wherein the drive is such that the speed of rotation of the circular blade is greater than the speed of rotation of the clamping roller.
12. A cutting device for longitudinally cutting a web substantially as hereinbefore described with reference to, and as illustrated in, Figure 1, Figures 2 and 4, and Figure 3 of the accompanying drawings.