WO1999008845A1

WO1999008845A1 - Rotary cutting device

Info

Publication number: WO1999008845A1
Application number: PCT/CH1998/000339
Authority: WO
Inventors: Heinz Keller
Original assignee: Inter Label Machines Ag
Priority date: 1997-08-14
Filing date: 1998-08-12
Publication date: 1999-02-25

Abstract

The invention concerns a device for rotary cutting comprising a cutting roll (1) and counter-roll (2) which can be contacted with each other so as to rotate together and located in a frame (12). The disclosed device comprises a pressure element (3) capable of being releasably placed in contact with the cutting roll (1) and pressed against it with adjustable prestressing force, by means of elastic elements (4; 20). The adjusted prestressing force is maintained substantially constant by an adjusting device (21).

Description

Rotary punching device

The invention relates to a device for rotary punching according to the preamble of patent claim 1.

Such devices are used, in particular, for punching self-adhesive label materials which are laminated onto a hard, siliconized carrier material, and for punching through self-adhesive composite materials, monopaper, films and other composite materials.

A large number of such devices are known from the prior art, all of which have the major disadvantage that the punching pressure must be monitored continuously in order to be able to maintain the punching quality in the required manner.

Since the punching pressure or the punching pressure preload changes depending on the preload force, temperature (depending on the running time and load) and punching speed (speed of the punching cylinder), spring rate of the housing and the effective punching force in such devices, the punching depth also changes (most important) Quality criterion for self-adhesive materials). Further considerations on this problem can be found in the literature, for example in "Fundamentals of Rotational Stamping Technology" 1991, Dr. Ing.Markus Bringmann in FlexoDruck 5-91. It is also known from the prior art that this change in the punching pressure bias can be displayed by means of hydraulic biasing systems and thus enables the operator to correct the change and to manually set the originally set punching pressure bias again.

The invention seeks to remedy this. The invention is based on the problem of creating a device for rotary punching, in which the punching bias pressure is matched to a minimum necessary, specific punching force (N / cm) and is kept essentially automatically constant.

The invention solves this problem with a device for rotary punching, which has the features of claim 1.

The solution according to the invention differs from the prior art in particular in that it does not attempt to achieve a more constant punching depth through a more stable and rigid construction of the device, but rather realizes this through an integrated regulation of the application of force by means of elastic elements.

Suitable as elastic elements are all types of metallic springs, gas springs or liquid springs, which have been described in detail by Steinhilper et Röper in "Machine and Construction Elements" Volume 3, for example. The advantages achieved by the invention can be seen essentially in the fact that

- The setting of the punching pressure preload can be done automatically when changing the tool

- The setting of the punching pressure preload is generally matched to the minimum necessary, specific punching force and is proportional to the active punching cylinder width

- The setting of the punching pressure preload is carried out evenly and symmetrically over the entire active punching cylinder width

- The setting of the punching pressure preload is variable and programmable

- The punching results are reproducible

- The set punching pressure preload is automatically kept constant

- Due to temperature influences, the punching pressure preload cannot be increased

- Temperature influences are automatically compensated and therefore have no influence on the punching quality

- The spring rate of the housing cannot have any influence on the punching pressure preload

- The support rings of the punching tool and the counter-punching cylinder are only loaded with the minimum necessary preload

- the running, resp. Support rings only have a minimal indentation depth (deformation) under load due to the minimally necessary preload due to the minimal impression depth the punching speed (deformation time behavior) can hardly influence the punching quality. Back-up rings and the punching cylinder are subject to significantly less wear, overloading due to the course of the web (greatly increased race ring pressure) or winding of the material web through the tool in the event of web break can result in longer tool lives the shortest set-up times can be achieved, a higher economic efficiency can be achieved.

A first preferred embodiment (A) of the invention consists in that the punching pressure preload is generated by means of a bellows cylinder which is pressurized with compressed air. This first version has the advantage that

- A simple and economical solution is achieved for small web widths

- The punching pressure preload can be set and kept constant by means of a pressure regulator and pressure gauge

- In combination with a controllable special valve (pressure and vacuum operation) the pressing device can be extended or retracted

- Working with a relatively large diameter range of punch cylinders, without additional adapters can - this combination enables a semi-automatic punch cylinder change in the simplest way.

A second preferred embodiment (B) of the invention consists in that the punching pressure pretension is generated by means of metallic pressure springs which are pretensioned to a desired value via tie rod spindles. The setpoint setting and any change in the punching pressure preload is detected by an electronic spring displacement measuring system. By automatically keeping the specified spring travel constant (position control), the punching pressure preload remains independent of the temperature, punching speed, spring rate of the housing and other influences. This second version has the advantage that the pre-tensioning forces required for larger web widths can be generated. Large diameter ranges can be driven by punching cylinders. This combination allows a semi-automatic changing of the punching cylinder in the simplest way and enables symmetrical and asymmetrical control.

The invention and further developments of the invention are explained in more detail below on the basis of the partially schematic representations of exemplary embodiments.

Show it: 1 shows a schematic illustration of the device according to the invention in accordance with embodiment (A) with a relaxed elastic element;

2 shows a schematic representation of the device according to the invention in accordance with embodiment (A) with a prestressed elastic element;

3 shows a schematic illustration of the device according to the invention in accordance with embodiment (B) with a relaxed elastic element; and

4 shows a schematic illustration of the device according to the invention in accordance with embodiment (B) with a prestressed elastic element;

The two embodiments (A and B) of the device for rotary punching according to the invention shown in FIGS. 1-4 essentially comprise a punch cylinder 1 and a counter cylinder 2, which can be brought into rotary engagement with one another and one with the punch cylinder 1 in a detachable manner Contactable pressing device 3, which by means of elastic elements 4; 20 can be pressed against the punching cylinder 1 with an adjustable pretensioning force (FIG. 2). The counter cylinder 2 is connected in a fixed position to the frame 12, while the punch cylinder 1, which can have different diameters depending on the punching format, can be inserted easily into the frame 12. The power transmission takes place via - attached to the pressing device 3 - rollers 11 directly on the laterally attached to the punch cylinder 1, respectively. Support rings 7.

The centerpiece of the device according to the invention is the pressing device 3, which can be brought into engagement with the punching cylinder 1 in a detachable manner.

In the embodiment A (FIGS. 1 and 2), this pressing device 3 comprises a lower plate 8 and a bellows cylinder 20 (FIG. 1) suspended in the frame 12 and acting as an elastic element.

On the lower plate 8 two rollers 11 are attached on each side, which frictionally with the running, respectively. Support rings 7 of the punch cylinder 1 can be brought into engagement. Thanks to the movable suspension of the lower plate 8 on the bellows cylinder 20, the rollers 11 can be pressed against the punching cylinder 1 by pressurizing the bellows cylinder 20 with compressed air, by changing the air pressure with a selectable preload force (spring force F). The elastic element in the form of a bellows cylinder 20 in connection with a control device 21 in the form of a commercially available pneumatic pressure regulator is able to change one of the operating conditions (temperature, punching speed etc.) to maintain independent, essentially constant pretensioning force between punch cylinder 1 and counter cylinder 2.

Another pressing device in embodiment B (FIGS. 3 and 4) comprises a lower plate 8 and an upper plate 9, which are held at a certain adjustable distance from one another by spacer elements 10. Elastic elements in the form of springs 4 are attached between the two plates 8, 9, which hold the two plates 8, 9 apart from one another in the absence of external loads at the maximum distance which the spacer elements 10 allow (FIG. 3).

On the lower plate 8 two rollers 11 are attached on each side, which with the running, respectively. Support rings 7 of the punch cylinder 1 can be frictionally engaged. Thanks to the resilient mounting of the lower plate 8, the rollers 11 can be pressed against the punching cylinder 1 with a selectable prestressing force (spring force F), the elastic elements in the form of springs 4 being shortened accordingly (FIG. 4). The spring travel s of the springs 4 determines (together with the spring rate c) the spring force F which is exerted on the punching cylinder 1 - and thus also between the punching cylinder 1 and the counter cylinder 2.

The application of force by the pressing device 3 takes place in this embodiment B in such a way that the upper plate 9 is moved downwards by means of tie rod spindles 23 actuated by the electric motor 22. Meet the rollers 11 on the Races 7 of the punch cylinder 1, the spring travel s of the springs 4 begins to shorten and the pretensioning force builds up at the predetermined spring rate c. A commercially available displacement sensor 5 between the upper plate 9 and lower plate 8 measures the spring travel s of the springs 4 (the deflection corresponds to the preload force - spring characteristic according to the spring rate c). If this electronic actual value of the sensor reaches the predetermined target value, the stop signal for the rotation of the tie rod spindles 23 is issued.

The displacement sensor 5 now continuously monitors the specified deflection. If the actual sensor value deviates from the target value, the change is compensated by rotating the tie rod spindles 23 without delay, and the predetermined pretensioning force is thus kept constant. The control device 21 acting on the springs 4 can compensate for any fluctuations in the changes occurring between the punch cylinder 1 and the counter cylinder 2 without delay. Such changes occur in conventional, rigidly constructed punching units, in particular due to the fact that thermal increases in the punching cylinder 1, or. cause an increase in the cylinder diameter. Due to the rigid placement of the punching cylinder 1 in conventional punching units, the contact force between the punching cylinder 1 and the counter cylinder 2 increases sharply and inevitably leads to a change in the punching quality. This problem is prevented by the present invention, since an increase in the biasing force compensated without delay, respectively. is prevented. The elastic means 4 can - as shown in FIGS. 1 to 4 - be metallic springs, preferably Hooke's spring, but any other type of elastic element can be used, ie also rubber springs, gas springs, pneumatic cylinders or liquid springs, which are used for this Use case with a control device 21 to be kept at constant force.

The setting of a pretensioning force for the punching pressure of 200 to 500 N per centimeter of active punch cylinder length, preferably of 300 to 350 N / cm active punch cylinder length, has proven to be optimal. In the case of punch cylinders 1 which are more worn, the pretensioning force should preferably be increased to up to 400 N / cm.

For practical applications, a spring travel s for sensor-based scanning of approx. 5 - 10 mm has proven to be optimal for Hookeschen springs for this range of preload force.

Claims

claims

1. Device for rotary punching with a punch cylinder (1) and a counter cylinder (2), which can be brought into rotary engagement with one another and are accommodated in a frame (12), characterized in that

A) a pressing device (3) which can be brought into engagement with the punching cylinder (1) in a detachable manner is provided, which can be pressed against the punching cylinder (1) by means of elastic elements (4; 20) with an adjustable pretensioning force; and

B) the set pretensioning force is kept essentially constant by means of a control device (21).

2. Device according to claim 2, characterized in that the counter-cylinder (2) is connected in a fixed position to the frame (12) and the biasing force is transmitted to the punching cylinder (1) via rollers (11) attached to the pressing device (3) is, preferably on races (7) attached to the side of the punch cylinder (1).

3. Device according to claim 1 or 2, characterized in that the elastic elements (4, -20) of the Hooke's spring type are with a spring travel s in the range of preferably 5 - 10 mm.

4. Device according to one of claims 1 to 3, characterized in that the elastic elements (4, -20) are metallic springs, rubber springs, gas springs, pneumatic cylinders or liquid springs (hydraulic cylinders).

5. Device according to one of claims 1 to 4, characterized in that the effective biasing force (spring force F) on the punch cylinder (1) is 200 to 500 N / cm active cylinder length, preferably 300 to 400 N / cm active cylinder length.

6. Device according to one of claims 1 to 5, characterized in that when using pneumatic or hydraulic cylinders as elastic elements (4; 20), the constant application of force via the control of the pneumatic or hydraulic pressure.