Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
This invention relates to an apparatus for automati-
cally adjusting the tension on materials being laminated or
joined together.
When manufacturing disposable diapers or like pro-
ducts, two film-like materials which have different moduli of
elasticity are fed to laminating rolls. However, the tension
on these materials must be limited to certain predetermined
ranges.
It i5 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 i
are too high, material tearing, slipping or bonding problems may '
result. As material elasticities change, web tensions will
~j change in the machine. This invention requires automatic adjust-
j able 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.
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The concept according to the present invention is to
il automatically vary the unwind system tensions of the two mater-
ials (within precise limits) in a fixed ratio equal to the ratio
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of their approximate average elasticities (expressed as units of
stretch per unit or unwind tension on the full material width).
The unwind systems will be varied automatically in order to
stabilize the reading on the downstream tension indicator to a
manually set target.
DESCRIPTION OF THE PRIOR ART
Photo-electric sensing devices are shown in United
States Patent No. 2,088,984 to Tandel. The position of the web
i8 measured rather than the thickness thereof.
' In the past, load cells and dancer arms have been
J 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.
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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
;J~j elongated web of~material with the speed and tension thereof
being adjustable.
United States Patent No. 3,510,374 to ~alker dis-
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closes a control apparatus for sensing a property of a movingweb and adjusting the moving web so that the desired property
is unifonm throughout the web.
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In United States Patent No. 3,107,679 to Pawlowski,
there is disclosed an automatic tension control device which
utilizes 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 utilizes 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 con-
trols 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 dis-
closes a tension monitoring and controlling means which includes
' a controller responsive to outpute of the tension sensing trans-
ducer thereof a reference tension selector for controlling
torque applied to the tension control roll to thereby control
the web tension.
SUMMARY OF THE INVENTION
I It is therefore an object of the invention to provide
an apparatus for maintaining a viable range of film material
tensions which is achieved from measuring the tension on the
i laminates from the laminating rolls.
In order to achieve the object of the invention,
there is provided a computerized converting machine wherein film !
fed from supply rolls are automatically tensioned at rates
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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 are 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 present invention thus provides an automatic tension
setting apparatus comprising a first supply roll for a first film
material, feed means for unwinding and feeding said first film
material, laminating means, a dancer arm engaging said first film
material, first pneumatic means for adjusting said dancer arm to
vary the tension on said first film material, a second film
material on a second supply roll, feed means for unwinding said
second film material to said laminating means, a second dancer arm
engaging said second film material, and second pneumatic means for
adjusting the position of said second dancer arm for varying the
tension on said second film material, a computer, and means for
measuring the tension on the laminate of said first film material
and said second film material operatively connected to said
computer to provide a signal thereto, said computer being
operatively connected to said first and second pneumatic means to
operate said first and second pneumatic means dependent on said
signal from said measuring means.
As well, the automatic tension setting apparatus may
also include a rotational sensor means for sensing the rotational
position of each said first and second dancer arms.
This invention also provides for an apparatus for
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laminating two different film materials fed at varying tensions
from supply rolls for said film materials comprising adjustable
dancer arms for engaging the film material, a computer, means for
initially setting the tension on said film materials, means
connected to said computer for controlling the position of said
dancer arms, means for measuring the tension on the laminate
connected to said computer so that the loads on the dancer arms
will be automtically regulated to control the tension on said
laminate.
By way of illustration but not limitation, an embodiment
of this invention will be hereinafter described with reference to
the drawing, in which:
Figure 1 is a schematic diagram of an apparatus for use
in a converting machine for automatically setting the tension of
film materials being laminated.
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DETAILED DESCRIPTION OF THE INVENTION
With continuing reference to the accompanying draw-
ing, the apparatus according to the invention serves to auto-
matically vary the tension on each of two film materials 12 and
14 to maintain the tensions thereon within desirable ranges.
The apparatus 10 includes supply rolls 16 and 18 for
film materials 12 and 14. Unwind motors 20 and 22 drive endless
belts 24 and 26 for unwinding film materials 12 and 14. Roll
sets 30 and 32 can be idlers, or driven, to "tendency driven"
(to reduce friction and drag on the web), which ser~e 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 film materials 12 and 14.
; The apparatus 10 includes a computer 38 or micro-
processor which controls the speed of motors 20 and 22 by out- ¦
, puts 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 about which the film
materials 12 and 14 are entrained. Air regulators 68 and 70
controlled by Lnputs 72 and 74 from the computer function with
j ~ associated pneumatically operated pistons to control the posi-
tlon of dancer arms 54 and 56.
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The position of the dancer arms 54 and 56 is deter-
mined by measuring devices 74 and 76 which send signals as in-
puts 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 lamina-
ting rolls 34 and 36.
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 and 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 of the laminating rolls 34 and 36 can be
independent. The speed of motor 20 is automatically adjusted to
keep/return the dancer arm 54 to a fixed position (midpoint or
horizontal in the Fig.). The speed of motor 22 is automatically
,i adjusted to keepjreturn the dancer arm 56 to a fixed position
,l (midpoint or horizontal in the Fig.). The air pressures or
loads on the two dancer arms are automatically regulated (in a
preset ratio) to keep the web tension at sensor 82 within a pre-
determined range.
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