EP0758942A1

EP0758942A1 - Automatic tangential cutting system

Info

Publication number: EP0758942A1
Application number: EP96905619A
Authority: EP
Inventors: Robert Baldan
Original assignee: A Celli Belgium SA
Current assignee: A Celli Belgium SA
Priority date: 1995-03-13
Filing date: 1996-03-11
Publication date: 1997-02-26
Also published as: DE29680162U1; CA2190186A1; BE1009187A5; WO1996028284A1

Abstract

Counter-cutters (11) are slidably mounted along a common shaft (12) and a linear positioning unit (13) parallel to said shaft includes a rail slidably engaged by a carriage (14) supporting a positioning actuator (15) controlled by a control device. The cutters (17) may be secured to the counter-cutters and slide along at least one guide rail (21) during lateral movement of the cutting units.

Description

AUTOMATIC TANCENTIAL CUTTING SYSTEM

The present invention is in the field of longitudinal cutting, also called slitting, of flexible materials, such as paper, nonwoven, plastic film or glass fibers. It relates more particularly to a tangential cutting system at high speed.

Mechanically, a cutting unit is made up of a blade and a counter blade, both circular and mounted on their respective supports. The knife is the assembly formed by the blade and its support. The counter blade and its possible support are called a counter blade. The assembly consisting of a knife and its counter knife is called the cutting unit. All the cutting units of a machine constitute a cutting system. The tangential cut means that the sheet is tangent to the counter knife, at the place of the cut.

The field of longitudinal cutting is constantly evolving. Manufacturers are constantly increasing the performance of their cutting systems to adapt to the continual diversification of products and to increase precision and cutting speeds.

Cutting systems include either independently powered counter knives or cutting rings mounted on a through shaft. On machines belonging to new generations, the most frequent problems are linked to the precision, speed and ease of positioning at the desired widths, to safety of use, as well as to obtaining cutting widths. very narrow. While it is easy to respond to each of the problems listed above separately, it is much less obvious to develop cutting systems with an adequate overall solution. These problems are briefly explained below.

1) Accuracy and speed of positioning

Positioning is the operation of adjusting the cutting widths. On most machines still in operation, positioning is done manually. This operation is relatively slow and the precision which can be obtained is limited. The operator's dexterity plays a major role in the quality of positioning.

If the positioning speed is not too important when the number of knives is low (3 to 5 knives), its importance becomes decisive when the number of knives on a machine reaches 40 or even 60 units. In these cases it is not uncommon to have to immobilize the machine for several hours to reposition the knives.

In the case of cutting rings mounted on a through shaft, the positioning of the cutting units to achieve the desired cutting widths can only be done manually. To do this, it is necessary to adjust the counter blades to the desired width and with the required details. For accuracy of less than 1 mm, the use of caliber is essential.

In addition to this adjustment of the counter blades, it is also necessary to adjust the knife in front of the counter knives, which constitutes an additional operation. There are many automatic positioning systems when the counter knives are driven with their individual motor, but with such systems it is not possible to achieve very narrow cutting widths (usually ± 200 mm).

The positioning operation requires in almost all cases a separate adjustment for the knives and for the counter knives since they are not connected to each other by a mechanical connection.

2) Sharpening of the counter knives

Sharpening the counterblades poses more particular problems when there is a grooved cylinder or cutting rings. In these cases, it is hardly conceivable to take the knives out of the machine to sharpen them, since this operation requires far too much time. In other cases, it is possible to easily disassemble the counter knives and replace them with others which have been sharpened outside the machine.

The counter knives are therefore sharpened on the machine. This solution in turn leads to a lot of drawbacks, such as: . the need for dedicated machine tools to sharpen the counter knives;

. more or less significant machine downtime; . the presence in the machine of fine metal filings resulting from the sharpening operation.

The usual operations on knives, namely the adjustment of the cutting width (against knives), the replacement of worn blades and various maintenance operations are manual interventions on very sharp elements. Unfortunately, this results in numerous hand injuries for operators. The use of suitable gloves can reduce this risk, but not eliminate it. In addition, wearing gloves slows down all of these knife adjustment and adjustment operations.

The ideal is to limit as much as possible the manual operations at the level of the cutting system.

3) Minimum cutting width

One characteristic which has also become increasingly important in recent years is the minimum cutting width. This minimum cutting distance represents the closest distance at which it is possible to bring the cutting units closer together.

When very narrow widths (<30 mm) are required, grooved cylinders are generally installed. The minimum cutting width depends mainly on the width of the knives, because if it is easy to obtain grooves very close to one another, it is much less easy to build very narrow knives.

The cutting rings also allow small cutting widths, but accompanied by the adjustment difficulties described above.

In the case of tangential cutting, the problem is to obtain cutting widths as small as pos¬ sible, easily adjustable, as well as easy replacement of worn counter blades. When each counter knife is equipped with its own drive motor, the dimensions of the latter very often limit the minimum cutting width to ± 200 mm, which is too large for a whole series of products. The counter-knives with independent motorization, even if they give very good results in terms of the quality of cut, do not therefore make it possible to obtain small cutting widths.

The invention provides a global solution to the problems mentioned above and proposes a tangential cutting system with several independent cutting units, which makes it possible to achieve both high speed and positioning accuracy and very wide cutting widths. weak, less than 200 mm.

This objective is achieved by a tangential cutting system as defined in the claims.

The attached drawing shows a perspective view, with cutaway, of a cutting system according to the invention. In this drawing, the various organs are designated as follows: 10 Frame

11 Counter knife

12 Common grooved axis carrying the counter knives

13 Linear unit 14 Trolley

15 Pneumatic cylinder

16 Counter blade

17 Knife

18 Pneumatic two-movement blade holder 19 Blade

20 Knife trolley

21 Linear guide rail for knives

22 Pneumatic piston for the connection between knife and counter knife in order to ensure the simultaneous movement of the two elements of the cutting unit

23 Position locking air chamber

24 rack

25 Knurled knob 26 Graduated ruler

The counter knives 11 are mounted on the common grooved axis 12 which can be driven in rotation. The counter knives can slide along the axis 12 and their positioning is done automatically by the linear positioning unit 13 under the control of a control device comprising a servo motor or a stepping motor and a digital controller with user interface and control software. Along the linear unit 13 slides the carriage 14 carrying a pneumatic cylinder 15 which positions each counter knife 11 quickly and precisely. The knives 17 are mounted on the carriages 20 capable of sliding along the guide rails 21 provided with ball bearings. Each knife has a holder pneumatic blade 18 with two movements and a blade 19, a pneumatic piston 22 for securing the knife to the associated counter knife to allow simultaneous lateral movement of the two elements of the cutting unit and an air chamber 23 to simultaneously block all cutting units. A knurled adjustment knob 25 cooperating with a rack 24 allows quick, precise and easy manual displacement of each cutting unit. The graduated rule 26 allows automated measurement of the position of the cutting units.

The advantages of the invention in terms of section are summarized below.

The system is capable of achieving positioning accuracy of the order of 0.1 mm. It is possible to foresee it on new machines or to adapt it on existing machines up to 6 m wide. The speed of the positioning operation is approximately 3 to 5 cutting units per minute.

Especially for machines requiring a large number of knives, as well as high precision, the invention makes it possible to reduce the time necessary to modify a set-up by a factor of 5 to 8, while increasing noticeably precision.

As the counter blades can easily be removed from the machine by simply removing the splined axis, sharpening can be done outside the machine. The use of a splined shaft makes it possible to combine the ease of replacement of the counter blades, present in the case of an individual motorization of the counter knives, and to obtain short minimum cutting distances para para - wheat to those obtained with cutting rings. The great advantage in terms of safety is the elimination of manual intervention on the knives for the positioning operation, this operation being indeed fully automated. Indeed, the pneumatic piston mounted on the head of the knife makes it possible to secure the knife and the counter-knife during the positioning. The alignment between the blade and the counter blade is thus ensured permanently. It is therefore not necessary to check this alignment manually before putting the knives into service.

A small minimum cutting distance up to ± 50 mm is obtained thanks to narrow guide rails and the splined axis to ensure the rotary drive of the counter knives, as well as to an appropriate design of the automatic cutting system. positioning of the knives so that there is no interference with this minimum cutting width.

Claims

1. Tangential cutting system comprising several cutting units consisting of a knife and a counter knife, characterized in that all the counter knives (11) are mounted so that they can slide along a common axis (12 ), and in that the system carries a linear positioning unit (13) extending parallel to the aforementioned common axis, the above-mentioned linear positioning unit comprising a rail along which slides a carriage (14 ) carrying a positioning cylinder (15) under the control of a control device.

2. System according to claim 1, characterized in that the control device comprises a digital controller.

3. System according to claim 1 or 2, characterized in that the common axis (12) above is a splined axis.

4. System according to any one of the preceding claims, characterized in that the knives (17) are mounted so that they can slide along at least one guide rail (21) provided with a ball bearing.

5. System according to any one of the preceding claims, characterized in that each knife com¬ carries a support (18) on which is fixed a means (22) for securing the knife against the knife.

6. System according to claim 5, characterized in that the means for securing the knife to the counter knife consists of a pneumatic piston.

7. System according to any one of the preceding claims, characterized in that each cou¬ pe unit comprises means (23) for locking the position of the cutting unit along the guide rail.

8. System according to any one of the preceding claims, characterized in that it comprises a graduated rule (26) parallel to the knife guide rail for the automated measurement of the position of the cutting units.