GB2170186A

GB2170186A - Detection and control of stretch in film material

Info

Publication number: GB2170186A
Application number: GB08531735A
Authority: GB
Inventors: Dennis Clark Elmore
Original assignee: Colgate Palmolive Co
Current assignee: Colgate Palmolive Co
Priority date: 1984-12-27
Filing date: 1985-12-24
Publication date: 1986-07-30
Also published as: AU581717B2; AU5170985A; IT1208729B; GB2170186B; GB8531735D0; IT8548970A0; CA1280680C; BE903958A; FR2575449B1; FR2575449A1

Abstract

A device for measuring and controlling the stretch in a web of film material to correspond to the predetermined stretch in a second web of material with both webs being fed to laminating rolls comprising a supply roll for the said first material, feed rolls for pulling the said first web of material from the said supply roll, and endless belt for supplying an initial tension to the said first web and operated by a motor. A dancer arm loaded by a pneumatically controlled piston to increase or decrease the tension on the first web of material, a photo-electric scanner for measuring the width or thickness of the said first web of material to provide an input to the said pneumatically operated piston and a sensor and computer for measuring the position of the dancer arm to provide a signal to the said motor to adjust initial tension on the said first web so that the said first web will be stretched an amount similar to the second web of material.

Description

SPECIFICATION Detection and control of stretch in film material The present invention relates to a device for assuring better lamination of film material. When webs of film material are fed to laminating rolls without the use of the present invention, they generally have different amounts of stretch thereon. Thus, when the laminated material relaxes, it may result in too much curl or warping. The present invention uses the concept that the width or thickness of the web is proportionately related to the amount of stretch thereon and, therefore, a photo-electric scanner is used for measuring the width of the web and imparting a signal to a pneumatically controlled dancer arm.

Photoelectric sensing devices are shown in U.S.

patent no. 2,099,984 to Tandel and the position of a web is measured.

In the past, load cells and dancer arms have been used to control the tension on a web being fed as disclosed in U.S. patent no. 2,753,128, as well as in Japanese Patent No. 44-12163 and British patent no. 1,371,760.

The U.S. Patent No. 2,627,296 to Secrest discloses an apparatus including means for adjusting the tension in a web of fabric.

In U.S. Patent No. 3,239,161 to Dutro et al there is disclosed a drive control mechanism which dispenses an elongated web of material with the speed and tension thereof being adjustable.

U.S. Patent Nol. 3,510,374 to Walker discloses a control apparatus for sensing a property of a moving web and adjusting the moving web so that the desired property is uniform throughout the web.

In U.S. Patent No. 3,107,679 to Pawlowski, there is disclosed an automatic tension control device which utilises either pneumatic or electrical circuitry to maintain the tension in a web of material substantially constant.

The U.S. Patent No. 3,762,125 to Prena discloses a device for controlling the lamination of one material onto another material which utilises a photocell 50, which is responsive to indicia 48 on the film "F" which sends the information to a control box 34 of a clutch 39, which controls the stretch rolls 38a and 38b to thereby keep the two webs lined up with one another.

U.S. Patent No. 4,347,993 to Leonard discloses a tension monitoring and controlling means which includes a controller responsive to outputs of tension sensing transducer thereof a reference tension selector for controlling torque applied to the tension control roll to thereby control the web tension.

According to one aspect of the present invention laminating apparatus comprises first and second feed paths respectively for first and second elastic materials, which feed paths merge at a laminating station, the tension in at least one of the materials in its flow path being variable by tension control means to adjust the stretch thereof prior to lamination, the tension control means including means for scanning the width and/or thickness of the material.

According to another aspect of the present invention laminating apparatus comprises first and second feed paths respectively for first and second stretchable films, which feed paths merge at a laminating station, one of said films having an elasticity which is matched by controlling the stretch of the other film, prior to reaching the lamination station, by measurements at a location in its feed path, of its width and/or thickness, and the application of a signal resulting from said measurement to stretch control means for said other film.

According to a specific arrangement the invention provides a device for testing and adjusting the amount of stretch in a first web of material for corresponding the amount of stretch in the said first material to that of the predetermined stretch in a second web of material, comprising a pair of laminating rolls, feed means for feeding the said first and second webs of the material to the said laminating rolls, a supply roll for the said first material, unwind means for applying an initial tension on the said first web of material, scanning means for scanning the width or thickness of the said first web of material, a dancer arm having an idler roll about which the said first web is entrained, control means for loading the said dancer arm upon a signal from the said scanning means, and sensor and computing means connected to the said control means and the said unwind means for applying initial tension on the said first web of material and the said control means to adjust the tension on the said first web of material so that the said material has a stretch equal to the predetermined stretch on the said second web of material.

The method according to the present invention may use a photo-electric scanner for scanning the width or thickness of a web of material to provide an input into a pneumatic actuator for a dancer arm to adjust the tension on a web of film material. The position of the dancer arm is in turn sensed by a sensor and fed to a computer which provides a signal to a motor operating an endless belt engaging the web of material to resist pulling of the web from a supply roll. Thus, the stretch in the web of film material can be equalised with that of the predetermined stretch in another web of film material when both are fed to laminating rolls so that there will be no warping of the laminated product.

The invention can be put into practice in various ways and one specific embodiment will be described by way of example, to illustrate the invention with reference to the accompanying drawing, which is a schematic diagram of an embodiment of a device in accordance with the present invention for adjusting the stretch in a web of film material.

In the accompanying drawing, there are provided a pair of laminating rolls 10 and 12 between which two webs 14 and 16 of film material are drawn for lamination thereof.

The amount of stretch on the material 16 is predetermined by measurement or other means. The device according to the present invention is for equalising the stretch in material 14 with the stretch in material 16 by utilising the fact that the amount of stretch will be proportionate to the width, or thickness, of the film material 14.

The material 14 is drawn from a supply roll 18 by driven feed rolls or by the laminating roll nip.

Initially, the tension on the material 14 is controlled by a dancer arm 32 which is pivotally mounted at 34, and which is loaded by a pneumatically controlled piston 46. An endless belt 26 driven by a motor 28, provides a brake on the material 14 as it leaves the coil 18, thus introducing tension into it.

The speed of the belt 26 is used to maintain the dancer arm in an operating range.

The material 14 passes round a roll 20, and then passes about an idler roll 30 on the dancer arm 32.

The material 14 then passes round rolls 22 and 24 and is pulled by the laminating rolls 10 and 12.

A photoelectric scanner 40, including a photoelectric cell and signalling means, is positioned to measure the width (or thickness) of the material 14 after it has passed around the idler roll 30, e.g. between rolls 22 and 24. The scanner 40 is electrically operatively connected to a pneumatic actuator 42, including a pressure regulator 44 connected to an air or pneumatic cylinder 46 for controlling the force of a piston 48. Thus, the signal from the scanner 40 determines the load on the dancer arm and hence the tension on the material 14 and the amount of stretch thereof.

There is a rotational sensor or potentiometer 50 for providing an electrical signal based on the rotational position of the dancer arm so as to provide a signal to a computer 52 or micro-processor associated with the motor 28.

Thus, the speed of the endless belt 26 is controlled by the motor 28 dependent on the signal from the rotational potentiometer 50 to control the initial stretch on the material 14 so that the stretch on the material 14 will be the same as the stretch on the material 16 being fed to the laminating rolls 10 and 12.

Claims

1. A device for testing and adjusting the amount of stretch in a first web of material for cor responding the amount of stretch in the said first material to that of the predetermined stretch in a second web of material, comprising a pair of lami nating rolls, feed means for feeding the said first and second webs of the material to the said lami nating rolls, a supply roll for the said first material, unwind means for applying an initial tension onthe said first web of material, scanning means for scanning the width or thickness of the said first web of material, a dancer arm having an idler roll about which the said first web is entrained, control means for loading the said dancer arm upon a sig nal from the said scanning means, and sensor and computing means connected to the said control means and the said unwind means for applying in itial tension on the said first web of material and the said control means to adjust the tension on the said first web of material so that the said material has a stretch seuql to the predetermined stretch on the said second web of material.

2. A device as claimed in Claim 1 in which the said scanning means includes a photo-electric cell.

3. A device as claimed in Claim 1 or Claim 2 in which the said sensor and computing means includes a potentiometer operatively electrically connected the said unwind means.

4. A device as claimed in Claim 1, 2 or 3 in which the said unwind means includes an endless belt engaging the said first web of material and a motor for driving the said endless belt.

5. A device as claimed in Claim 1, 2, 3 or 14 in which the said unwind means includes an endless belt engaging the said first web of material and a motor for driving the said endless belt, the said sensor and computing means including a potentiometer connected to the said motor speed control.

6. A device for testing and adjusting the amount of stretch in a first web of material for corresponding the amount of stretch in the said first material to that of the predetermined stretch in a second web of material, comprising a pair of laminating rolls, feed means for feeding the said first and second webs of material to the said laminating rolls, a supply roll for the said first material, unwind means for applying an initial tension on the said first web of material, scanning means for scanning the width or thickness of the said first web of material, a dancer arm having a idler roll about which the said first web is entrained, a pneumatic cylinder having a piston therein, the said piston being connected to the said dancer arm, compressor means actuated by said scanning means for actuating the said piston to load the said dancer arm, and sensor and computing means connected to the said control means and the said unwind means for applying initial tension on the said first web of material to vary said unwind means and the said control means to adjust the tension on the said first web of material so that the said material has a stretch equal to the predetermined stretch on the said second web of material.

7. A device as claimed in Claim 6 in which the said means for feeding the said first web of material to the said laminating rolls include a plurality of driven feed rolls, the said scanning means including a photo-electric cell.

8. A device as claimed in Claim 6 or Claim 7 in which said means for feeding the said first web of material to the said laminating rolls include a plurality of driven feed rolls, the said scanning means including a photo-electric cell, the said sensor and computer means including a potentiometer operatively electrically connected to the said unwind means.

9. A device as claimed in Claim 6, 7 or 8 in which the said means for feeding the said first web of material to the said laminating rolls include a plurality of driven feed rolls, the said scanning means including a photo-electric cell, the said sensor and computer means including a potentiometer operatively electrically connected to the said unwind means, the said unwind means including an endless belt engaging the said first web of mate rial, and a motor for driving the said endless belt.

10. A device as claimed in Claim 6, 7, 8 or 9 in which said means for feeding the said first web of material to the said laminating rolls include a plurality of driven feed rolls, the said scanning means including a photo-electric cell, the said sensor and computer means including a potentiometer operatively electrically connected to the said unwind means, the said unwind means including an endless belt engaging the said first web of material, and a motor for driving the said endless belt, the said sensor and computer means including a rotational potentiometer connected to the said dancer arm for measuring the position of the said dancer arm and computing a signal therefrom to send to the said motor for adjusting the speed of the said motor.

11. Laminating apparatus comprising first and second feed paths respectively for first and second elastic materials, which feed paths merge at a laminating station, the tension in at least one of the materials in its flow path being variable by tension control means to adjust the stretch thereof prior to lamination, the tension control means including means for scanning the width and/or thickness of the material.

12. Laminating apparatus comprising first and second feed paths respectively for first and second stretchable films, which feed paths merge at a laminating station, one of said films having an elasticity which is matched by controlling the stretch of the other film, prior to reaching the lamination station, by measurements at a location in its feed path, of its width and/or thickness, and the application of a signal resulting from said measurement to stretch control means for said other film.

13. A device as claimed in Claim 1 substantially as specifically described herein with reference to the accompanying drawing.

14. Apparatus for laminating materials incorporating a device as claimed in any one of Claims 1 to 11.