GB2173485A

GB2173485A - Apparatus for controlling tension in webs fed to lamination

Info

Publication number: GB2173485A
Application number: GB08531734A
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: 1986-10-15
Also published as: CA1281622C; BE903959A; FR2575448A1; FR2575448B1; AU5171185A; IT8548959A0; IT1208726B; AU580124B2; GB8531734D0; GB2173485B

Abstract

An apparatus for automatically adjusting the tension on materials being laminated or joined comprising a pair of supply rolls for the said materials. A feed assembly is provided for unwinding and feeding the film materials to laminating rolls. Dancer arms are provided for adjusting the tension on the film materials. Computer actuated pneumatic assemblies automatically adjust the position of the dancer arms dependent on a signal to the computer from a device measuring the tension on the laminate from the laminating rolls.

Description

SPECIFICATION Apparatus for controlling tension The present invention relates to an apparatus for automatically adjusting the tension on materials being laminated or joined together.

When manufacturing disposable diapers or like products, two film-like materials which have different moduli of elasticaly are fed to laminating rolls. However, the tension on these materials must be limited to certain predetermined ranges.

It is found that most converting machines have a tension operating range requirement in order to run well. The range is determined by the general qualities of the materials to be run, requiring certain specific machine pull station speed settings and unwind tension levels.

For instance, if tensions are too low, the material will not track properly. If tensions are too high, material tearing, slipping or bonding prolems may result. As material elasticities change, web tensions will change in the machine. According to one aspect, the present invention provides automatic adjustable tension devices on the unwind systems of the two materials to be laminated or joined, a downstream tension detector on the laminate or joined web and a control logic system.

In the method according to the present invention the unwind system tensions of the two materials are automatically varied (within precise limits) in a fixed ratio equal to the ratio of their approximate average elasticities (expressed as units of stretch per unit of unwind tension on he full material width). The unwind systems are varied automatically in order to stabilise or return the reading on the downstream tension indicator to a manually set target.

Photo-electric sensing devices are shown in United States patent no. 2,088,984 to Tandel.

The position of the web is measured rather than the thickness thereof In the past, load cells and dancer arms have been used to control the tension on a web being fed as disclosed in United States patent no. 2,753,128, as well as in Japanese patent no. 44-12163 and British patent no.

1,371,760.

The United States patent no. 2,627,296 to Secrest discloses an apparatus including means for adjusting the tension in a web of fabric.

In United States 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.

United States patent no. 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 United States 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 United States 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.

United States patent no. 4,437,993 to Leonard discloses a tension monitoring and controlling means which includes a controller responsive to output of the tension sensing transducer thereof a reference tension selector for controlling torque applied to the tension controlroll to therby control the web tension.

The present invention aims to provide an apparatus for maintaining a viable range of film material tensions which is achieved from measuring the tension on the laminates from the laminating rolls.

According to another aspect of the present invention, laminating apparatus comprises first and second feed paths for first and second materials which merge at laminating means, the tension and/or stretch in each material being controlled by first and second control means in the respective flow paths under the control of a computer which is arranged to receive at least one input feed-back signal from each of the first and second flow paths, and a tension measuring device located downstream of the laminating means for measuring a characteristic of the laminate and feeding a signal, dependent thereon, to the computer.

According to another aspect of the present invention, there is provided a computerised converting machine wherein film fed from supply rolls are automatically tensioned at rates commensurate with the relative elasticity of the film materials. Pneumatically operated pivoted dancer arms engage the film material for adjusting the tension thereon. The positions of the dancer arms are measured and fed as inputs to the computer of the converting machine as is a signal from a device for measuring the final tension on the laminate as it comes from the laminating rolls.

The invention may 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 ac companying drawing which is a schematic dia gram of an apparatus in accordance with the present invention for use in a converting ma chine for automatically setting the tension on film materials being laminated.

The apparatus according to the present in vention shown in the accompanying drawing serves automatically to vary the tension on each of two film materials 12 and 14 to maintain the tensions thereon within desired ranges.

The apparatus 10 includes supply rolls 16 and 18 respectively for the film materials 12 and 14. Unwind motors 20 and 22 drive endless belts 24 and 26 for controlling the unwinding of the film materials 23 and 14. Roll sets 30 and 32 can be idlers, or driven, to "tendency driven" (to reduce friction and drag on the web), which serve to deliver the film materials 12 and 14 to laminating rolls 34 and 36, which are separately driven, or a like device for laminating and/or joining the film materials 12 and 14.

The apparatus 10 includes a computer 38 or microprocessor which controls the speed of the motors 20 and 22 by respective outputs 40 and 42. The approximate modulus of elasticity of each of the film materials 12 and 14 is manually set in the computer 38 as inputs.

Pivotally mounted at 50 and 52 are dancer arms 54 and 56 carrying idler rolls 58 and 60 respectively about which the film materials 12 and 14 are entrained. Air regulators 68 and 70, controlled by outputs 72 and 74 from the computer, function with associated pneumatically operated pistons 75 and 76 to control the positions of the dancer arms 54 and 56.

The rotational positions of the dancer arms 54 and 56 are determined by rotational sensor or measuring devices located at the pivots 50 and 52 and which send signals as inputs 78 and 80 to the computer 38.

A measuring device 82 measures the final tension on the laminate of the two materials 12 and 14 fed from the laminating rolls 34 and 36. The device 82 sends a signal 84 to the computer.

The computer 38 is programmed so as to maintain the tension on the film materials 12 and 14 at optimum range so as to prevent accidental bonding, tearing or improper feed causing failures in the laminate, by adjusting the position of the dancer arms 54, 56 and/or the speed of the unwind motors dependent mainly upon the input from the tension measuring device 82 and the initial manually set inputs.

The speed ofthe laminating rolls 34 and 36 can be independent. The speed of the motor 20 is automatically adjusted to keep/return the dancer arm 54 to a fixed position (midpoint or horizontal in the drawing). The speed of the motor 22 is also automatically adjusted to keep/return the dancer arm 56 to a fixed position (midpoint or horizontal in the drawing).

The air pressures or loads on the two dancer arms are automatically regulated (in a preset ratio) to keep the web tension at the sensor 82 within a predetermined range.

Claims

1. An automatic tension setting apparatus comprising a first supply roll for a first film material, feed means for unwinding and feeding the said first film material, laminating means, a dancer arm engaing the said first film material, first pneumatic means for adjusting the said dancer arm to vary the tension on the said first film material, a second film material on a second supply roll, feed means for unwinding the said second film material to the said laminating means, a second dancer arm.

engaging the said second film material, and second pneumatic means for adjusting the position of the said second dancer arm for varying the tension on the said second film material, a computer, and, downstream of the laminating means, means for measuring the tension on the laminate of the said first film material and the said second film material operatively connected to the said computer to provide a signal thereto, the said computer being operatively connected to the said first and second pneumatic means to operate the said first and second pneumatic means dependent on the said signal from the said measur- - ing means

2. An apparatus as claimed in Claim 1- in which in the said first and second dancer arms are each pivotally mounted and located between the said supply rolls and the said laminating means.

3. An apparatus as claimed in Claim 1 or Claim 2 in which the said computer includes means for manually setting the comparative elasticity therein of the said first and second film materials.

4. An automatic tension setting apparatus comprising a first supply roll for a first film material, first feed means for unwinding and feeding the said first film material to a laminating means, a dancer arm engaging the said first film material, first pneumatic means for adjusting the said dancer arm to vary the tension on the said first film material, a second film material on a second supply roll, second feed means for unwinding the said second film material to the said laminating means, a second dancer arm engaging the said second film material, and second pneumatic means for adjusting the position of the said second dancer arm for varying the tension on the said second film material, a computer, and means for measuring the tension on the laminate of the said first film material and the said second film material operatively connected to the said computer to provide a signal thereto, the computer being operatively connected to the said first and second pneumatic means to operate the said first and second pneumatic means dependent on the said signal from the said measuring means, and rotational sensor means for sensihg the rotational position of each of the said first and second dancer arms.

5. An apparatus as claimed in Claim 4 in which the said rotational sensor means are operatively connected to the said computer so that the rotational positions of said dancer arms are furnished as input signals to the said computer.

6. An apparatus as claimed in Claim 4 or Claim 5 including further input mens to the said computer for manually setting the relative elasticity of the said first and second film materials.

7. An apparatus for laminating two different film materials fed at varying tensions from supply rolls for the said film materials comprising adjustable dancer arms for engaging the film material, a computer, means for initially setting the tension on the said film materials, means connected to the said computer for controlling the position of the said dancer arms, means for measuring the tension on the laminate connected to the said computer so that the loads on the dancer arms will be automatically regulated to control the tension on said laminate.

8. Laminating apparatus comprising first and second feed paths for first and second materials which merge at laminating means, the tension and/or stretch in each material being controlled by first and second control means in the respective flow paths under the control of a computer which is arranged to receive at least one input feed-back signal from each of the first and second flow paths, and a tension measuring device located downstream of the laminating means for measuring a characteristic of the laminate and feeding a signal, dependent thereon, to the computer.

9. An apparatus as claimed in Claim 1 substantially as specifically described herein with reference to the accompanying drawing.

10. An apparatus for laminating materials incorporating apparatus as claimed in any one of Claims 1 to 10.