GB2026990A

GB2026990A - Severing Device to Protect Machines Handling Continuously Moving Webs

Info

Publication number: GB2026990A
Application number: GB7926953A
Authority: GB
Original assignee: ROBUR WERKE ZITTAU VEB
Current assignee: ROBUR WERKE ZITTAU VEB
Priority date: 1978-08-03
Filing date: 1979-08-02
Publication date: 1980-02-13
Also published as: NL7903803A; SU1217765A1; IT7949929A0; DD138185B1; DE2919348A1; CH639348A5; GB2026990B; DD138185A1; IT1162361B

Abstract

A severing device to protect a machine against excessively high tensile forces in a web (1) running therethrough is (preferably) located near to a take-up reel (16) of a web winding machine and comprises a web guide roller (3) displaceable pivotally by tensile forces in the web and biassing means, such as air-spring bellows (6), to prevent displacement of the guide roller (3) by a tensile force below a predetermined value. At least one bell crank lever arm (7) is articulated to the guide roller (3), and one or a respective number of knives (9) are carried by the or each of the bellcrank lever arms (8) to cut the web when the tensile force therein exceeds the predetermined value. <IMAGE>

Description

SPECIFICATION Severing Device to Protect Machines for the Treatment of Running Material Webs The present invention relates to a severing device to protect against excessively high web tension forces in machines for the treatment of running material webs of textile, paper, synthetic material or similar, wherein these webs are wound on reels, and in which the webs to be treated display high running speeds. In these machines, it can be necessary for different reasons that they must be stopped in the shortest possible time by emergency switch-off.

Known machines for the treatment of running material webs are generally stopped by braking the drive motors. The material webs are wound on reels after they have left the actual machine.

The reel is driven by a motor coupled to the reel core or the reel axle or by a roller engaging at the reel periphery. With the introduction of the socalled large reels, on which in the case of the textile material webs several thousand metres can be wound, rotating masses of several tons are present with a nearly full reel. These rotating masses must be braked in the shortest possible time in the case of an emergency switch-off. This occurs either through the drive of the large reel or through the tension forces to be transmitted by the material web or by both together.

Occasionally, friction brakes are also arranged at the spigot of the reel core.

With the material web speeds and thereby also rotational speeds of the reels increasing constantly in consequence of technical advance, there arise moments of inertia which can no longer be managed in the required manner in the way described above. A state arises in the case of an emergency switch-off, in which the material web guide elements of the machine come to a standstill earlier than the large reel. In the case of material webs of high tensile strength, this leads to the transmission of large forces from the still rotating reel to the material web guide elements installed as rollers in the machine.

When the tension forces transmitted by the still rotating reel through the material web are greater than the strength of the material web guide elements looped by the material web and already braked, then destruction or irreversible deformation of the material web guide elements takes place.

According to the present invention there is provided a severing device for use as a protective device in a machine for treating running material webs, the severing device comprising a material web guide element displaceable under the influence of tension forces of the web, biassing means to prevent the guide element being displaced under the influence of a tension force below a predetermined magnitude thereof, at least one lever articulated to the guide element, and knife means so mounted to the or each lever as to cut into the material web when the tension force thereof exceeds said predetermined magnitude.

Preferably the or each lever comprises an angled double-arm lever.

Advantageously the biassing means comprises one or more air spring bellows.

An embodiment of the invention will now be more particularly described by way of example and with reference to the accompanying drawings in which: Fig. 1 shows a side elevation of a severing device embodying the invention used in a machine for the treatment of textile material webs, and Fig. 2 shows a plan view of the severing device.

Referring now to the drawings, a material web 1 runs over material web guide elements, rollers 2, 3, 4 and 5. The bearings of the roller 3 rest on air spring bellows 6, which can be loaded by an adjustable air pressure. Two levers each having two angled arms 7 and 8 are articulated parallel to one another and connected to the bearings of the roller 3 through arm 7. The end of the lever arm 8 carries a knife 9, which is opposed by a second knife 10. The material web 1 runs between the knives 9 and 10 and the cutting edge of the knife 9 is inclined to the surface of the material web 1. A support 11 is fastened to a frame 12 of the textile machine and receives a bearing 1 3 with a rotational centre 14 about which the double armed levers 7, 8 are journalled.

The normal position of the levers 7,8 is fixed by an adjustable abutment 1 5 and the adjustable air pressure of the air spring bellows 6. The reel on which the material web 1 is wound is shown as 16.

When the material web tension forces acting on the roller 3 exceed the maximum reaction force predetermined by the pressure in the air spring bellows, then the air spring bellows 6 are compressed. The roller 3 moves and the knife 9 is moved towards the knife 10 by means of the twoarmed levers 7, 8 and cuts the material web 1 or cuts into it. The material web 1 needs to be cut into at only one place. It tears in consequence of the large material web tension forces, in a direction generally transverse to the material web running direction. The material web tension forces acting on the material web guide elements of the textile machine are thereby so limited that they can no longer damage the machine parts. The damage arising through the material web 1 cut transversely is insignificant compared with the prevented machine damage.

In place of one knife 9, several knives can be provided. The severing device is usable in textile machines in which several material webs run simultaneously.

Claims

1. A severing device for use as a protective device in a machine for treating running material webs, the severing device comprising a material web guide element displaceable under the influence of tension forces of the web, biassing

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Severing Device to Protect Machines for the Treatment of Running Material Webs The present invention relates to a severing device to protect against excessively high web tension forces in machines for the treatment of running material webs of textile, paper, synthetic material or similar, wherein these webs are wound on reels, and in which the webs to be treated display high running speeds. In these machines, it can be necessary for different reasons that they must be stopped in the shortest possible time by emergency switch-off. Known machines for the treatment of running material webs are generally stopped by braking the drive motors. The material webs are wound on reels after they have left the actual machine. The reel is driven by a motor coupled to the reel core or the reel axle or by a roller engaging at the reel periphery. With the introduction of the socalled large reels, on which in the case of the textile material webs several thousand metres can be wound, rotating masses of several tons are present with a nearly full reel. These rotating masses must be braked in the shortest possible time in the case of an emergency switch-off. This occurs either through the drive of the large reel or through the tension forces to be transmitted by the material web or by both together. Occasionally, friction brakes are also arranged at the spigot of the reel core. With the material web speeds and thereby also rotational speeds of the reels increasing constantly in consequence of technical advance, there arise moments of inertia which can no longer be managed in the required manner in the way described above. A state arises in the case of an emergency switch-off, in which the material web guide elements of the machine come to a standstill earlier than the large reel. In the case of material webs of high tensile strength, this leads to the transmission of large forces from the still rotating reel to the material web guide elements installed as rollers in the machine. When the tension forces transmitted by the still rotating reel through the material web are greater than the strength of the material web guide elements looped by the material web and already braked, then destruction or irreversible deformation of the material web guide elements takes place. According to the present invention there is provided a severing device for use as a protective device in a machine for treating running material webs, the severing device comprising a material web guide element displaceable under the influence of tension forces of the web, biassing means to prevent the guide element being displaced under the influence of a tension force below a predetermined magnitude thereof, at least one lever articulated to the guide element, and knife means so mounted to the or each lever as to cut into the material web when the tension force thereof exceeds said predetermined magnitude. Preferably the or each lever comprises an angled double-arm lever. Advantageously the biassing means comprises one or more air spring bellows. An embodiment of the invention will now be more particularly described by way of example and with reference to the accompanying drawings in which: Fig. 1 shows a side elevation of a severing device embodying the invention used in a machine for the treatment of textile material webs, and Fig. 2 shows a plan view of the severing device. Referring now to the drawings, a material web 1 runs over material web guide elements, rollers 2, 3, 4 and 5. The bearings of the roller 3 rest on air spring bellows 6, which can be loaded by an adjustable air pressure. Two levers each having two angled arms 7 and 8 are articulated parallel to one another and connected to the bearings of the roller 3 through arm 7. The end of the lever arm 8 carries a knife 9, which is opposed by a second knife 10. The material web 1 runs between the knives 9 and 10 and the cutting edge of the knife 9 is inclined to the surface of the material web 1. A support 11 is fastened to a frame 12 of the textile machine and receives a bearing 1 3 with a rotational centre 14 about which the double armed levers 7, 8 are journalled. The normal position of the levers 7,8 is fixed by an adjustable abutment 1 5 and the adjustable air pressure of the air spring bellows 6. The reel on which the material web 1 is wound is shown as 16. When the material web tension forces acting on the roller 3 exceed the maximum reaction force predetermined by the pressure in the air spring bellows, then the air spring bellows 6 are compressed. The roller 3 moves and the knife 9 is moved towards the knife 10 by means of the twoarmed levers 7, 8 and cuts the material web 1 or cuts into it. The material web 1 needs to be cut into at only one place. It tears in consequence of the large material web tension forces, in a direction generally transverse to the material web running direction. The material web tension forces acting on the material web guide elements of the textile machine are thereby so limited that they can no longer damage the machine parts. The damage arising through the material web 1 cut transversely is insignificant compared with the prevented machine damage. In place of one knife 9, several knives can be provided. The severing device is usable in textile machines in which several material webs run simultaneously. Claims

1. A severing device for use as a protective device in a machine for treating running material webs, the severing device comprising a material web guide element displaceable under the influence of tension forces of the web, biassing means to prevent the guide element being displaced under the influence of a tension force below a predetermined magnitude thereof, at least one lever articulated to the guide element, and knife means so mounted to the or each lever as to cut into the material web when the tension force thereof exceeds said predetermined magnitude.

2. A severing device as claimed in claim 1, wherein the or each lever comprises an angled double-arm lever.

3. A severing device as claimed in either claim 1 or claim 2, comprising at least two levers, the knife means comprising a single knife blade mounted to all of the levers.

4. A severing device as claimed in either claim 1 or claim 2, comprising at least two levers, the knife means comprising a plurality of knife blades each mounted to a respective one of the levers.

5. A severing device as claimed in any one of the preceding claims, the biassing means comprising one or more air spring bellows.

6. A severing device as claimed in any one of the preceding claims, the knife means having a cutting edge inclined to the surface of the material web.

7. A severing device for use as a protective device in a machine for treatment running material webs and substantially as hereinbefore described with reference to the accompanping drawings.

8. A machine for treating running material webs, the machine comprising a take-up reel at the output end of the machine and a severing device as claimed in any one of the preceding claims, the device being mounted in the immediate vicinity upstream of the take-up reel.