GB2170485A

GB2170485A - Stretch centrol of materials to be laminated or joined

Info

Publication number: GB2170485A
Application number: GB08531732A
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: 1986-08-06
Also published as: FR2575451B1; GB8531732D0; FR2575451A1; IT1208728B; AU5170785A; BE903956A; AU585921B2; CA1279247C; IT8548969A0

Abstract

In a device for controlling the stretch on two web materials being laminated, a web of a first material is fed by feed rolls past at least two tension load cells to a laminating roll where a web of a second material, whose stretch has been measured or determined independently or with a similar device is also delivered. Signals proportional to the stretch of the second web material are delivered to a computer as inputs, the computer providing an output to the unit necessary to control the stretch on the first web so it equals the stretch on the second.

Description

SPECIFICATION Stretch control of materials to be laminated or joined The present invention relates to a device for controlling the stretch of materials being joined and, more particularly, to a device for assuring equal stretch in two materials being laminated or joined by varying the web tensions of one or more of the materials being joined.

The prior art shows use of control systems to achieve the constant tension on individual or all materials to be laminated and required operator skill and careful monitoring of quality of the final laminate.

This is disclosed in an article entitled "The Art of Roll to Roll Adhesive Laminating" as published in Converter magazine, December, 981.

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

1,371,760.

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

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

The U.S. 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.

U.S. Patent No. 3,107,679 to Pawlowski discloses an automatic tension control device which utilises either pneumatic or electric circuitry to maintain the tension in a web of materials substantially constant.

U. S. Patent No. 3,672,125 to Prena discloses a device for controlling the lamination of one material onto another material 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 rollers 38a and 38b to thereby keep the two webs lined up with one another.

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

The present invention aims to provide a device capable of carrying out a process of controlling the tension on at least one of two webs of material being laminated so that the materials being laminated have equal stretch.

According to one aspect of the present invention, a method of laminating a first material of unknown elasticity with a second material comprises determining the degree of stretch in the second material as it approaches the laminating means and applying tension so as to automatically stretch the first material so that it arrives at the laminating means with substantially the same degree of stretch as the second material.

According to another aspect of the present invention a device for stretch control of materials to be laminated and/or joined, comprises a first material supply roll for supplying material having an unknown elasticity, laminating rolls, first feed rolls for delivering the said first material to the said laminating rolls, means supplying a second material to the said laminating rolls in a predetermined stretched condition, and means for applying tension to the said first material to automatically stretch the said first material to an extent substantially the same as that of the said second material so that the first material and the said second material will be joined while stretched by susbstantially equal amounts.

According to a further aspect of the present invention a device for stretch control of two separate webs of material being laminated comprises first and second supply rolls for first and second webs of material, laminating rolls, means for feeding the said second web to the said laminating rolls at a predetermined stretch, means associated with the said laminating rolls for measuring the stretch on the said second web of material to the said laminating rolls, and means for stretching the said first web to an extent substantially the same as the stretch on the said second web of material.

The stretch control device according to the present invention includes a supply roll of a first web material. Feed rolls with a tach generator feed back unit deliver the first material past at least two tension load cells before delivering the first material to a laminating roll where a second material has been delivered and whose stretch has been measured or determined independently or with a similar device. The signals of the tach generator and the load cells are delivered to a computer as inputs which provide an output to the unit necessary to control the stretch on the first web so it equals the stretch on the second. The necessary single output signal (to control the tension on the first material) controls the speed of an unwind belt for the first material.Alternatively, a dancer arm is used and, therefore, there are two output signals; one output signal is for the speed of the unwind belt which is controlled by the position of the dancer arm (being ideally a position control only); the second necessary output signal controls the tension in the first material and can be to a sliding weight positioner on the dancer arm or it can be a directly-applied load on the dancer arm such as an air pressure signal to an air cylinder.

The invention may be put into practice in various ways and a number of specific embodiments will be described to illustrate the invention with reference to the accompanying drawings, in which Figure 1 is a schematic diagram of a stretch control device according to the present invention; and Figure 2 is a schematic diagram of a modified form of stretch control device according to the present invention.

In the accompanying drawings like reference numerals designate similar throughout the various views.

In Figure 1 there is provided a first supply roll 10 for a first material 12. The material 12 has an elasticity "E" and is drawn from the supply roll under the control of an unwind belt 38, over a roll 14, and thence to a tension load cell 16 for adjustably varying the tension on the material. The belt 38 is driven by a motor 32. The tension load cell 16 is shown with a tension spring 100 as an optional buffer. Figure 2 illustrates an alternative, using a dancer arm 80 as a tension adjust feature which may be used in lieu of the load cell 16.

The material 12 is then fed past a- roll 18 and then through feed rolls 19 with which a tach generator 20 is associated and then past a tension load cell 22 and thence through laminating rolls 24 and 26 which draw the materials through the apparatus. A tach generator or encoder 28 is associated with the laminating roll 24.

A second material 30 is also fed through the laminating rolls 24 and 26.

The belt 38 is an endless friction belt and controls the tension on the material 12 leaving the roll 10.

Any well-known means can be used to provide an intitial stretch on the second material 30.

Inputs signals L1, L2, T1, T2 are taken from the tachometer generators 20 and 28, and the tension load cells 16 and 22, respectively and fed to a microprocessor 34 along the lines 36.

The microprocessor or computer 34 is operatively electrically connected by the conductors 36 to the various tension load cells and tach generators.

Corrective action is taken by adjusting the speed of the D.C. motor 32 for the material unwind by means of a signal from the microprocessor 34 along the line 105 to speed up or slow down the material unwind which directly affects the value of L and T1.

The equations or algorithms used in the microprocessor are derived as follows.

Step 1. Taking Hooke's Law:

and rearranging

Equation (1) Step 2. Substituting for L to find E:

Equation (2) Step 3. Substituting E back to Equation #1 and calculating L.

Equation (3) Step 4. Set L1 and L2 at constant speeds or values and manipulate T1 to maintain L near a target value.

In the above equations (1) to (3) E (an unknown value) = Apparent or calculated elasticity of the material 12.

L = Free-length (relaxed length of material per product per minute).

L1 = Linear feed rate of first feed rolls 19, i.e. stretched length of material per product per minute entering the feed roll 19. Rolls 14, 16, 18 may be driven at the same rate as the feed rolls 19.

L2 = Linear feed rate of laminating rolls 24 and 26, i.e. stretched length of material 30 per product per minute entering the laminating rolls.

T1 = Tension in the material 12 prior to the first feed rolls 19.

T2 = Tension in the material 12 after the drawing step, i.e. between the feed rolls 19 and laminating rolls 24 and 26.

L is calculated from Equation #3 by the microprocessor 34 at intervals and compared to a set point or target value.

Corrective actiqn taken as mentioned above can be in fixed increments or can be proportional to the size of the difference between "Calculated L" and "Target L." It is to be understood that the load cells may be placed in any selected loction based on the location of the laminating rolls in situ.

The embodiment shown in Figure 2 is similar to that of Figure 1. In this embodiment the initial friction on the material 42 pulled from the supply roll 40 is imposed by an endless belt 44. The dancer arm 80 is supported by the web of material 42 on a roll 50 and this is one determinant of the web tension.

The material 42 is passed over a first roll 48, then the dancer arm roll 50 and over a tension load cell roll 52. The material 42 is then passed through feed rolls 54 with which a tach generator unit is associated and thence another tension load cell 56 and thence through between laminating rolls 58 and 60. A tach generator or encoder 62 is associated with the laminating roll 58. The tach generators and tension load cells feed their input to a microprocessor or computer 64 which feeds output signals to the load on the dancer arm and/or to the motor speed of the motor 46 driving the unwind belt. The computer 64 is connected to the tach generators and tension load cells through conductors 66. The computer is programmed in accordance with the equations set forth in connection with Figure 1 to control the stretch of the material 12 to be the same as the stretch of the material 30. The corrective action, if needed, is to change T, by changing the load or the moment arm on the dancer arm 80 by means of a pneumatic or other dancer arm controller 82 which receives a computer output signal via a line 66A. When the dancer arm 80 begins to move, the unwind motor speed will be automatically adjusted to return the dancer arm 80 to a control position. A feed-back, representative of the rotational position of the dancer arm 80 is obtained from a sensor 81, which supplies a signal to the computer 64, via line 66B. It is to be understood that the dancer arms may be placed in any selected location based on the location of the laminating rolls in situ.

The computer can control both materials to the same relaxed length (Target L) should each material be fitted with the device of the present invention.

Claims

1. A method of laminating a first material of unknown elasticity with a second material which comprises determining the degree of stretch in the second material as it approaches the laminating means and applying tension so as to automatically stretch the first material so that it arrives at the laminating means with substantially the same degree of stretch as the second material.

2. A method as claimed in Claim 1 which comprises drawing the first material off a source of supply and applying a controlled resistance to said drawing off so as to stretch the first material by a controlled variable amount, and in which the length of the first material per unit of time is measured as it passes a first location spaced from the point of lamination and its length per unit of time is measured again as it is laminated, and the tension on the first material is measured at second and third locations on either side of the first location so that in its passage to the laminating means the first material passes the second location, then the first location and then the third location, and the values of length and tension together with the known degree of stretch of the second material are used to compute what variation in stretch in the first material is needed to make its stretch when laminated substantially the same as that of the second material and the resistance to drawing off is varied so as to produce any necessary change in stretch of the first material.

3. A method as claimed in Claim 1 substantially as specifically described herein with reference to Figure 1 or Figure 2 of the accompanying drawings.

4. A device for stretch control of materials to be laminated and/or joined comprising: a first material supply roll for supplying material having an unknown elasticity, laminating rolls, first feed rolls for delivering the said first material to the said laminating rolls, means supplying a second material to the said laminating rolls in a predetermined stretched condition, and means for applying tension to the said first material to automatically stretch the said first material to an extent substantially the same as that of the said second material so that the first material and the said second material will be joined while stretched by substantially equal amounts.

5. A device as claimed in Claim 4 in which there is a tach generator asscociated with a set of feed rolls located between the said supply roll and the said laminating rolls for controlling the means for applying tension to the said first material.

6. A device as claimed in Claim 5 in which the tach generator is associated with the first feed rolls.

7. A device as claimed in any one of Claims 4 to 6 in which the means for applying tension to the said first material is a tension load cell.

8. A device for stretch control of two separate webs of material being laminated comprising: first and second supply rolls for first and second webs of material, laminating rolls, means for feeding the said second web to the said laminating rolls at a predetermined stretch, means associated with the said laminating rolls for measuring the stretch on the said second web of material, means for feeding the said first web of material to the said laminating rolls, and means for stretching the said first web to an extent substantially the same as the stretch on the said second web of material.

9. A device as claimed in Claim 8, including a tach generator for measuring the stretch on the said first web between the said supply roll for the said first web of material and the said laminating rolls.

10. A device as claimed in any one of Claims 4 to 9 in which the said means for stretching the said first web includes at least two tension load cells.

11. A device as claimed in any one of Claims 4 to 10 in which the said means for stretching the said first web includes at least two tension load cells, and a tach generator for measuring the stretch on the said first web between the said supply roll for the said first web of material and the said laminating rolls, the said tach generator being electrically operatively connected to the said tension load cells.

12. A device for stretch control of web material comprising first and second supply rolls for supplying first and second materials, laminating rolls, means for feeding the first material to the said laminating rolls, a computer, first tach generator means connected to the said computer for measuring the stretch on the said first material, first tension load cell means connected to the said computer for controlling the stretch on the said first material in accordance with the input to the computer from the said first tach generator means, the said second material being fed to the said laminating rolls and the second tach generator means for measuring the stretch on the said second material and feeding the measured stretch to the said computer, the said computer comparing the stretch on both the said first and second materials for signalling to increase or decrease the stretch on the said first material so that the first and second materials are substantially equally stretched at the stage at which they are laminated.

13. A device as claimed in Claim 4 substantially as specifically described herein with reference to Figure 1 or Figure 2 of the accompanying drawings.

14. Apparatus for laminating materials incorporating a device as claimed in any one of Claims 4 to 13.