GB2072563A

GB2072563A - Sheet material processing e.g. cutting or creasing machine

Info

Publication number: GB2072563A
Application number: GB8107285A
Authority: GB
Original assignee: CAVAGNA E
Current assignee: CAVAGNA E
Priority date: 1980-03-27
Filing date: 1981-03-09
Publication date: 1981-10-07
Also published as: FR2479068A1; JPS56146699A; IT8020960A0; ES8207012A1; SE8101293L; ES500163A0; IT1131092B; DE3108691A1; GB2072563B

Abstract

Respective upper and lower tool-holders 1, 7 are movable across the width of a web P, e.g. of paper, on a rigid structure having transverse beams 4, 9. Each tool- holder has a motor 3 or 8 for driving it along the associated beam 4 or 9 by means of a pinion 13 or 13% and a rack 14 or 14%, and a braking device 2 or 10 for locking the tool-holder at a selected location. The motors and the braking devices are under electronic control. <IMAGE>

Description

SPECIFICATION Sheet material processing, e.g. cutting or creasing machine This invention relates to a machine for acting on a web of sheet material at one or more locations spaced across its width.

- When paper, cardboard, or laminated plastics sheet is to be cut to obtain strips therefrom having a defined width, it is necessary to use machines having a plurality of tool-holder units which can be exactly moved into the different working position, in order to have strips with a constant width. This occurs also with respect to the creasing of strips.

Up to now rope drive cutting machines have been used, but their accuracy is poor, owing to expansion of the ropes, to the change of their cross-section caused by temperature gradients, and to the distortion caused by wear. A chain drive has also been used, but also in this case the wear of the pins of the several links forming the chain gives rise to a change of their pitch and to innaccuracies in the size. Lastly, screw drives have been used, but they can drive two toolholder units at most, apart from being slow.

As a result of all the aforesaid inaccuracies, tolerances ranging from about 1 mm to about 3 mm have to be accepted, which circumstance is broadly troublesome for the subsequent operations and particularly remarkable in creasing operations.

At the present state of the art, a better result is achieved by fluid-pressure means, but dead times persist during the positioning operation, and furthermore the installation of fluidpressure means is rather complicated, thereby increasing the costs.

What is desired is a machine which is capable of reaching a cutting accuracy within a tolerance of about 0.1 mm. It is also desirable to reduce the operating costs by reducing the positioning time and causing the change between two operation modes and/or dimensions to be executed without stopping the machine, which, in turn, can be located upstream of a paper machine.

The present invention provides a machine for acting on a web of sheet material at one or more locations across its width as it passes through the machine, comprising a rigid supporting structure, and at least one tool-holder unit having an upper tool-holder and a lower tool-holder, the tool-holders being mounted on the supporting structure for movement across the width of the web, each tool-holder having a motor for driving it across the width of the web and means for immobilizing it relative to the supporting structure, the machine including electronic control means for controlling the motors and the immobilizing means in order to position the or each tool-holder unit at a given location.

In particular the invention provides a cutting and/or creasing machine for webs of paper, paperboard, or plastics laminates, which comprises two or more tool-holder unit sets comprised each of upper and lower toolholders supported by a stiff supporting structure, and an electronic control device adapted to position the individual tool-holder units at defined locations on the stiff supporting structure and to energize the individual motors driving each upper and lower tool-holders and to cause the tools of the upper tool-holders to cooperate with the tools of the lower toolholders, each tool holder unit having a braking or a pneumatic or electro-magnetic locking device.

Preferably, each tool-holder has an electromechanical positioning device comprising a pinion which cooperates with a rack to move the tool-holder, under control of the electronic control means, the tools being hand or electrically driven.

In a preferred embodiment there are toolholder units sets, which are mounted so as to be capable of continuously working in series with paper machines in subsequent positions, in one of which one set of tool-holder units is selectively performing a cutting or creasing operation, and in a second one the other set of tool-holder units is in a rest position or is performing a second operation.

More preferably there are three tool-holder unit sets, which are mounted so as to be capable of continuously working in series with paper machines in subsequent positions, in one of which one set of tool-holder units is performing a cutting or creasing operation, in the second one the second set of tool-holder units is at the rest position or is performing a second operation, and in the third one the third set of tool-holder units remains in the rest position, in a tool-change position or in a redundancy position.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic front elevation of a cutting or creasing machine fitted with cutting tools; Figure 2 is a section taken along line ll-ll of Fig. 1; Figure 3 is an enlarged detail of Fig. 2, showing a front tool-holder unit in a rest position; Figure 4 is a front elevation of the took holder unit of Fig. 3; Figure 5 shows a part-sectioned fragmentary front elevation of a tool-holder unit, in which the tools are creasing tools.

Figs. 1 to 4 illustrate a cutting machine A having three front tool-holder units B and three rear tool-holder units B'. Each toolholder unit is comprised of a upper tool-holder 1 which can be moved by an electric motor 3 along a transverse upper beam 4 of the ma chine framework, and a lower tool-holder 7 which can be moved by an electric motor 8 along a transverse lower beam 9 of the machine framework. The beams 4 and 9 are provided with respective racks 1 4 and 14' cooperating with respective pinions 1 3 and 13' driven by the respective motors 3 and 8.

As shown in Fig. 3 by way of example, within each tool holder 1 a pneumatic or electromagnetic locking or braking device is provided, here represented as a pad 2 which can bear on the beam 4; alternatively, the locking device may be axially connected to the motor 3. Within the lower tool-holder 7 a braking device is also provided, here represented as a locking pad 10.

Each upper tool-holder 1 supports a tool in the form of a circular cutter 5, whereas each lower tool-holder 7, supports a counter-tool in the form of a circular counter-cutter 6. The tool 5 held by the upper tool-holder 1 is driven by a motor 11, whereas the countertool 6 held by the lower tool-holder 7 is driven by a motor 12. The upper tool-holders 1 are each provided with upper and lower rollers 1 6 running in upper and lower guideways 1 7 in the beam 4, whereas the lower tool-holders 7 are each provided with front and rear rollers 1 5 running in front and rear guideways 18 in the beam 9.

Fig. 1 shows only the front set of toolholder units of the machine, which can comprise any number (three in the illustrated embodiment) of transversely movable toolholder units distributed across the machine, the number three not being limitative. As shown in Fig. 2, in a rear position, spaced as much as required by the material to be worked, a similar second set B' of tool-holder units is provided. If a spare set is desired to assure a greater reliability of continuous operation a third set of tool-holder units similar to the sets B, B' can be provided. In operation only one of the sets (for example the set B is working, while the other one or ones are in a rest or re-equipment position or being moved to new positions.

A motor (not shown) in each upper toolholder 1 is capable of moving the tool 5 vertically, for separating or bringing into cooperation the tool 5 and the counter-tool 6.

The tool 5 is movable between an upper, rest position (indicated by numeral 5 in Figs. 2 and 3) and a lower, operative position (indicated by numeral 5' in Figs. 2 and 3).

Fig. 5 shows the upper and the lower toolholders 1 and 7 in the case in which the tool is a male creasing tool 19, whereas the counter-tool is a female creasing tool 20.

The positioning operation will be now described, because for the first time it is performed in machines for continuously working paper or plastic laminates.

Assuming that one has to cut or crease a web P of paper or cardboard or plastics laminate lengthwise into continous gauged strips, various commands for the positioning of the units B, B' will be entered into an electronic or card programmer (not shown), each command relating to a unit comprised of an upper tool-holder 1 and a lower tool-holder 7.

Upon receipt of an electric signal from the programmer by one of the units, the braking devices 2 and 10 will be released, the cutter 5 (or the male creasing tool 19) will be raised from the counter-cutter 6 (or the female creasing tool 20), and the motors 3 and 8 will be energized so that they rotate the respective gears 1 3 and 13' engaging the respective racks 14 and 14', in order to move the toolholders 1 and 7 into the position previously determined on the programmer. The programmer, by means of a revolution counter (an encoder or a transducer), computes the distance travelled by the unit and upon reaching the determined value stops the motors 3 and 8 and simultaneously appiies the braking devices 2 and 10.

The positioning of the tool-holder units, therefore, is obtained without clearances or distortions of drive means.

Now the working cycle starts, which comprises the steps of energizing the motors 11 and 1 2 driving the tools and the counter-tools respectively, and lowering the tools in the programmed manner, i.e. the cutters 5 (or the male creasing tools 19) of the selected operative stations, until they cooperate with the associated counter-tools, i.e. the counter cutters 6 (or the female creasing tools 20). This operation can also be carried out by hand.

Claims

1. A machine for acting on a web of sheet material at one or more locations across its width as it passes through the machine, comprising a rigid supporting structure, and at least one tool-holder unit having an upper tool-holder and a lower tool-holder, the toolholders being mounted on the supporting structure for movement across the width of the web, each tool-holder having a motor for driving it across the width of the web and means for immobilising it relative to the supporting structure, the machine including electronic control means for controlling the motors and the immobilising means in order to position the or each tool-holder unit at a given location.

2. A machine as claimed in Ciaim 1, in which each motor drives a pinion engaging with a rack on the supporting structure.

3. A machine as claimed in Claim 1 or 2, in which each immobilising means includes a braking or locking element movable into and out of engagement with the supporting structure.

4. A machine as claimed in any of Claims 1 to 3, in which the upper tool-holder has means for raising and lowering a tool held by it.

5. A machine as claimed in any of Claims 1 to 4, in which the upper tool-holder holds a cutter and the lower tool-holder holds a counter-cutter.

6. A machine as claimed in any of claims 1 to 4, in which the tool-holders hold respective male and female creasing tools.

7. A machine as claimed in any of claims 1 to 6, having at least one first, upstream tool-holder unit and at least one second, downstream tool-holder unit.

8. A machine as claimed in claim 7, having at least one third tool-holder unit downstream of the second.

9. A machine as claimed in any of claims 1 to 8, having at least two tool-holder units spaced across the width of the web.