CA2030843A1 - Process of controlling the film thickness of blow-formed and axially and preferably biaxially stretched tubular films - Google Patents
Process of controlling the film thickness of blow-formed and axially and preferably biaxially stretched tubular filmsInfo
- Publication number
- CA2030843A1 CA2030843A1 CA002030843A CA2030843A CA2030843A1 CA 2030843 A1 CA2030843 A1 CA 2030843A1 CA 002030843 A CA002030843 A CA 002030843A CA 2030843 A CA2030843 A CA 2030843A CA 2030843 A1 CA2030843 A1 CA 2030843A1
- Authority
- CA
- Canada
- Prior art keywords
- film
- oven
- tubular
- tubular film
- blow
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 238000000034 method Methods 0.000 title claims abstract description 16
- 238000009826 distribution Methods 0.000 claims abstract description 20
- 238000000071 blow moulding Methods 0.000 claims abstract description 9
- 230000002093 peripheral effect Effects 0.000 claims abstract description 7
- 238000010438 heat treatment Methods 0.000 claims abstract description 5
- 238000010096 film blowing Methods 0.000 description 2
- 229920001169 thermoplastic Polymers 0.000 description 2
- 239000004416 thermosoftening plastic Substances 0.000 description 2
- 238000007664 blowing Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000004513 sizing Methods 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
- B29C55/28—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of blown tubular films, e.g. by inflation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/25—Component parts, details or accessories; Auxiliary operations
- B29C48/92—Measuring, controlling or regulating
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C2948/00—Indexing scheme relating to extrusion moulding
- B29C2948/92—Measuring, controlling or regulating
- B29C2948/92009—Measured parameter
- B29C2948/92114—Dimensions
- B29C2948/92152—Thickness
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C2948/00—Indexing scheme relating to extrusion moulding
- B29C2948/92—Measuring, controlling or regulating
- B29C2948/92504—Controlled parameter
- B29C2948/9258—Velocity
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C2948/00—Indexing scheme relating to extrusion moulding
- B29C2948/92—Measuring, controlling or regulating
- B29C2948/92504—Controlled parameter
- B29C2948/92609—Dimensions
- B29C2948/92647—Thickness
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C2948/00—Indexing scheme relating to extrusion moulding
- B29C2948/92—Measuring, controlling or regulating
- B29C2948/92819—Location or phase of control
- B29C2948/92923—Calibration, after-treatment or cooling zone
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C2948/00—Indexing scheme relating to extrusion moulding
- B29C2948/92—Measuring, controlling or regulating
- B29C2948/92819—Location or phase of control
- B29C2948/92933—Conveying, transporting or storage of articles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
- B29C48/09—Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels
- B29C48/10—Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels flexible, e.g. blown foils
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Shaping By String And By Release Of Stress In Plastics And The Like (AREA)
Abstract
ABSTRACT
PROCESS OF CONTROLLING THE FILM THICKNESS OF BLOW-FORMED
AND AXIALLY AND PREFERABLY BIAXIALLY STRETCHED TUBULAR
FILMS
Tubular films made in an extruding and blow-forming plant are collapsed and are subsequently axially and preferably biaxially stretched in that they are re-inflated to form an inflated tubular film or expanded to form a tubular film. That inflated or expanded tubular film is then moved through an oven, from which the film is withdrawn and re-collapsed while moving at a velocity which is higher than the feeding speed in accordance with the desired stretching ratio. In order to ensure that the stretched tubular films have a substantially uniform thickness distribution throughout their periphery, the film thickness of the stretched tubular film which has emerged from the oven is measured around the tubular film before or after it has been collapsed and in dependence on the thus measured thicknesses of the peripheral profile the thickness distribution around the peripheral profile of the tubular film formed in the extruding and blow-forming plant is so controlled that any deviation from the average film thickness of the film which has been stretched in the oven, which deviation has been caused by a non-uniform heating of the film and possibly to other disturbing influences exerted on the film in the oven, will substantially be compensated.
PROCESS OF CONTROLLING THE FILM THICKNESS OF BLOW-FORMED
AND AXIALLY AND PREFERABLY BIAXIALLY STRETCHED TUBULAR
FILMS
Tubular films made in an extruding and blow-forming plant are collapsed and are subsequently axially and preferably biaxially stretched in that they are re-inflated to form an inflated tubular film or expanded to form a tubular film. That inflated or expanded tubular film is then moved through an oven, from which the film is withdrawn and re-collapsed while moving at a velocity which is higher than the feeding speed in accordance with the desired stretching ratio. In order to ensure that the stretched tubular films have a substantially uniform thickness distribution throughout their periphery, the film thickness of the stretched tubular film which has emerged from the oven is measured around the tubular film before or after it has been collapsed and in dependence on the thus measured thicknesses of the peripheral profile the thickness distribution around the peripheral profile of the tubular film formed in the extruding and blow-forming plant is so controlled that any deviation from the average film thickness of the film which has been stretched in the oven, which deviation has been caused by a non-uniform heating of the film and possibly to other disturbing influences exerted on the film in the oven, will substantially be compensated.
Description
- 2~
P~OCESS OF COrJTROLLI~lG 'll~lE ~ILM '~'HI~KNES~ 0~ B~OW-FORr~ED
AND AXIALLY AND PRE~ERABLY BI~XIALL'f S'~ETCHED ~UBULAR
FI~MS
BACKG~OUND OF ~E~E INVENTIOrJ
Field of the Inven-tion ~ his invention relates to a proce~ of controlling the film thicknes~ of a blow~formed and axially and preferably biaxially stretched tubular film, which when it has been ~ormed in an extruding and blow-forming plant is collapsed and ~ubsequently re-inflated to form an inflated tubular film or expanded to form a tubular film and in an inflated or expanded state is moved through an oven, from which the film is withdrawn and re-collapsed while moving at a velocity which is higher than the feeding speed in accordance with the desired stretching ratio.
Tubular films which have been made by that process, which i9 known from Published German Application 20 57 255, have the disadvantaga that their thickness `` -`
varies around their periphery. Said variation in thickness i9 not only due to the variation of the thickness of the blow-formed tubular film as it enters the furnace or stretching tunnel but is particularly due also to the fact that the tubular film is not uniformly heated as it is stretched in the oven. A
tubular film which is not uniformly heated in the oven will exhibit a varying stretching behavior so that thicknes~ variations around the tubular film will result during the stretching e~en when the tubular film entering the oven ha~ a substantially uniform thickness around its periphery.
; -.
.
.
- , , ~
. .. ~ -. .. . : -: . . -.
.- : ~ , , ::~ -2 ~ ftJ 3 ~
In the proce~s known ~rom Published German ~pplication 20 57 255 the ~-tretching o~ the re-expanded ~nd heated tubular film iB accompanied by thickness variations not only becau~e the heating ia not uniform but also because, e.g., the thicknes~ di~tribution around the -tubular film is influenced by the geometric condi-tions and this may result in a thickness variation of the film as it is stretched~ Non-uniform geornetric conditions which rnay result in a variation of the thickness of the film as it i9 ~tretched will par-ticularly arise in the transitional region between the collapsed film and the tubular film which has been inflated or expanded to a tubular or cylindrical shape.
For this reason it is an object of the invention to provide a proces~ which is of the kind described hereinbefore and which can be used to produce drawn tubular films which are made from synthetic thermoplastics and which in a stretched state~have a aubstantially uniform thickness distribution around their periphery. ~hia means that it is desired that the stretched tubular films made by the known process should have a substantially uniform thickness distri-bution in a narrow tolerance range around their periphery and should have thicknesses which do not differ or differ only slightly from the average thicknes~.
In a proce~s which i8 of the kind de~cribed first hereinbefore that object is accomplished in accordance with the invention in that the film thickness .. . . :
:: . : , : , : , , :
~ . . .. . . -,, . ... ~ . . . . . . ..
: ; :: - . , . : : , -: . : . :
:: : ..
.
P~OCESS OF COrJTROLLI~lG 'll~lE ~ILM '~'HI~KNES~ 0~ B~OW-FORr~ED
AND AXIALLY AND PRE~ERABLY BI~XIALL'f S'~ETCHED ~UBULAR
FI~MS
BACKG~OUND OF ~E~E INVENTIOrJ
Field of the Inven-tion ~ his invention relates to a proce~ of controlling the film thicknes~ of a blow~formed and axially and preferably biaxially stretched tubular film, which when it has been ~ormed in an extruding and blow-forming plant is collapsed and ~ubsequently re-inflated to form an inflated tubular film or expanded to form a tubular film and in an inflated or expanded state is moved through an oven, from which the film is withdrawn and re-collapsed while moving at a velocity which is higher than the feeding speed in accordance with the desired stretching ratio.
Tubular films which have been made by that process, which i9 known from Published German Application 20 57 255, have the disadvantaga that their thickness `` -`
varies around their periphery. Said variation in thickness i9 not only due to the variation of the thickness of the blow-formed tubular film as it enters the furnace or stretching tunnel but is particularly due also to the fact that the tubular film is not uniformly heated as it is stretched in the oven. A
tubular film which is not uniformly heated in the oven will exhibit a varying stretching behavior so that thicknes~ variations around the tubular film will result during the stretching e~en when the tubular film entering the oven ha~ a substantially uniform thickness around its periphery.
; -.
.
.
- , , ~
. .. ~ -. .. . : -: . . -.
.- : ~ , , ::~ -2 ~ ftJ 3 ~
In the proce~s known ~rom Published German ~pplication 20 57 255 the ~-tretching o~ the re-expanded ~nd heated tubular film iB accompanied by thickness variations not only becau~e the heating ia not uniform but also because, e.g., the thicknes~ di~tribution around the -tubular film is influenced by the geometric condi-tions and this may result in a thickness variation of the film as it is stretched~ Non-uniform geornetric conditions which rnay result in a variation of the thickness of the film as it i9 ~tretched will par-ticularly arise in the transitional region between the collapsed film and the tubular film which has been inflated or expanded to a tubular or cylindrical shape.
For this reason it is an object of the invention to provide a proces~ which is of the kind described hereinbefore and which can be used to produce drawn tubular films which are made from synthetic thermoplastics and which in a stretched state~have a aubstantially uniform thickness distribution around their periphery. ~hia means that it is desired that the stretched tubular films made by the known process should have a substantially uniform thickness distri-bution in a narrow tolerance range around their periphery and should have thicknesses which do not differ or differ only slightly from the average thicknes~.
In a proce~s which i8 of the kind de~cribed first hereinbefore that object is accomplished in accordance with the invention in that the film thickness .. . . :
:: . : , : , : , , :
~ . . .. . . -,, . ... ~ . . . . . . ..
: ; :: - . , . : : , -: . : . :
:: : ..
.
- 3 - ~ v~
of the ~tretched tubular film which has emer~ed from the oven is measured around the tubular film before or after it has been collapsed and in dependence on the thu3 measured thicknesse~ of the peripheral profile the thicknes~ di~tribution around the peripheral profile of the tubular film form~d in the exbruding and blow-forming plant i9 90 controlled that any deviation from the average film thickne~ of the fil~ which ha~ been stretched in the oven, which deviation has been cau~ed by a non-uniform heating of the film and possibly to o-ther disturbing influences exerted on the film in the oven, will substantially be compensated. In the proces~
in accordance with the invention the profile of the inflated or expanded tubular film entering the oven has such a thickness distribution around its periphery that any thickness variations which result around the tubular film owing to non-uniform heat distribution3 in the oven and/or structural or geometric conditions will be compensated. In accordance with the invention the inflated or expanded tubular film which enters the oven has a profile having such a non-uniform thickness distribution around its periphery that the heat distri-bution and the geometric and structural conditions which affect the tubular film as it is expanded in the oven will have the result that the stretched tubular film has a sub~tantially uniform thickness distribution around its periphery. ~ -.
By known control or automatic control processes carried out in the extruding and blow-forming plant it is en~ured that the tubular film entering the oven has such a thickness di~tribution that the ~tretched tubular film will have a ~ubstantially uniform thicknes~ around its . . ,. :
,,, . i - , . . ., . .-"
- .. . . , : , . .. .. .
VJ 3 ~
periphery. The desired thickness di~tribution arou~d the periphery of the tubular film entering the oven can preferably be ~btained by the proces~ which is kno~m from German Patent Specifica-tion 30 14 989. '~hat known process can be carried out to make tubular films having a desired varying thiclcness distribution around their periphery. It will be appreciated that different control or automatic processes may be used to provide desired -thickness distributions around the periphery of tubular films, provided that such processes can produce the same results.
In the process in accordance with the invention it is necessary to flnd out how thickne~s deviations of the stretched film emerging from the oven can be changed -`
by a change of the thickness distribution of the profile of the film entering the oven. The dependencies can empirically be determined so that the required thickness distributions of the film entering the oven can be provided by the known control processes. It is merely essential to measure the thickness distribution around the profile of the stretched tubular film so that the thickness profile of the tubular film entering the oven can so be controlled or automatically controlled that the stretched tubular film will have a substantially uniform thickness around its periphery.
The thickness distribution around the stretched tubular film can be measured by known processes immedi~
ately after the tubular film has emerged from the oven.
Alternatively, the thickness distribution around the tubular film can be measured when -the film has been collapsed. It is also possible to take a sample from the stretched tubular film for a measurement of the thickness distribution of the film around its periphery.
. .: . .
.,: . ... . - -:
.
: - : . , , ~3~ll3 The extruded and blow-forrned tubular film which has been collapsed can be re-inflated by known processes, e.g., by the processes described in Publi~hed German Application 22 63 623 and in German Patent Specifica-tion 31 19 006.
The inflation ratio can be contro]led to control the stretching ratio in the peripheral direction.
Biaxially stretched tubl~ar films will even be obtained if, in the process known from Published German Applica-tion 20 57 255, the tubular film is inflated to have a desired diameter when entering the oven and that diameter is kept constant during the travel through the oven.
The single figure of the drawing i8 a side elevation showing an extruding and blow-forming plant and a succeeding apparatus for stretching re-inflated tubular films in an oven.
~ ' Detailed Description of the Preferred Empodiment An illustrative embodiment of the invention ;
will now be described more in detail with reference to the drawing.
The extruding and blow-forming plant comprises a conventional extruder 1, which supplies molten synthetic thermoplastics to a film-blowing head 2J : .
which is also known. ~he blow head 2 is provided with blowing means for inflating the tubular film 4 and with known cooling rings 3. The tubular film 4 which has been extruded from the film-blowing head 2 ;
"
,. . .: ~ .: ,: . :, .. .. . . .. - : . : . ~ . .. :, .
: :, . : , ~ ; ., ::: :
- 6 - 2~3~
~nd has been in~lated move~ through sizing Mean~ 5 and is subsequently collap~ed b~; means of plate~ 6 and fla~ten-ing rol.lers 7. The thus collapsed tubu:Lar film ~ is then moved to squeeze rolls 9, possibly through an interposed holdlng mechanism, which i~ not ~hown but is known per se. The collapsed tubular film ~ is then re-inflated to form an inflated tubular film. '~he mean~ Eor inflating are of l~lown type and for ~his reason are not described in detail herein.
The inflated tubular film 10 passes through a heating oven 11 and is subsequently delivered via collapsing means to squeeze rolls 13. Said squeeze rolls 13 are succeeded by a take-up 14 for winding up the stretched tubular film at a velocity which i9 higher than the velocity at which the -film is .
fed to the squeeze rolls 9. It is apparent from the ~
drawing that a capacitive thicl~ness sensor 15 is ~ -provided closely behind the oven and comprises a revolving measuring head 16. ~he measured-value si~nals generated by that measuring head are delivered to a computer 17, which delivers signals to the several temperature-control segments in the blow head ~.
The control of the thickness distribution around the tubular film 10 entering the oven is pref-erably controlled by the process described in German Patent Specification 30 14 989, in which the measured thicknesses of the stretched film are converted to such a thickness distribution of the tubular film entering the oven that the stretched tubular film will have the desired uniform thickness distribution.
, .: : : . ....... .
, .
. ~
of the ~tretched tubular film which has emer~ed from the oven is measured around the tubular film before or after it has been collapsed and in dependence on the thu3 measured thicknesse~ of the peripheral profile the thicknes~ di~tribution around the peripheral profile of the tubular film form~d in the exbruding and blow-forming plant i9 90 controlled that any deviation from the average film thickne~ of the fil~ which ha~ been stretched in the oven, which deviation has been cau~ed by a non-uniform heating of the film and possibly to o-ther disturbing influences exerted on the film in the oven, will substantially be compensated. In the proces~
in accordance with the invention the profile of the inflated or expanded tubular film entering the oven has such a thickness distribution around its periphery that any thickness variations which result around the tubular film owing to non-uniform heat distribution3 in the oven and/or structural or geometric conditions will be compensated. In accordance with the invention the inflated or expanded tubular film which enters the oven has a profile having such a non-uniform thickness distribution around its periphery that the heat distri-bution and the geometric and structural conditions which affect the tubular film as it is expanded in the oven will have the result that the stretched tubular film has a sub~tantially uniform thickness distribution around its periphery. ~ -.
By known control or automatic control processes carried out in the extruding and blow-forming plant it is en~ured that the tubular film entering the oven has such a thickness di~tribution that the ~tretched tubular film will have a ~ubstantially uniform thicknes~ around its . . ,. :
,,, . i - , . . ., . .-"
- .. . . , : , . .. .. .
VJ 3 ~
periphery. The desired thickness di~tribution arou~d the periphery of the tubular film entering the oven can preferably be ~btained by the proces~ which is kno~m from German Patent Specifica-tion 30 14 989. '~hat known process can be carried out to make tubular films having a desired varying thiclcness distribution around their periphery. It will be appreciated that different control or automatic processes may be used to provide desired -thickness distributions around the periphery of tubular films, provided that such processes can produce the same results.
In the process in accordance with the invention it is necessary to flnd out how thickne~s deviations of the stretched film emerging from the oven can be changed -`
by a change of the thickness distribution of the profile of the film entering the oven. The dependencies can empirically be determined so that the required thickness distributions of the film entering the oven can be provided by the known control processes. It is merely essential to measure the thickness distribution around the profile of the stretched tubular film so that the thickness profile of the tubular film entering the oven can so be controlled or automatically controlled that the stretched tubular film will have a substantially uniform thickness around its periphery.
The thickness distribution around the stretched tubular film can be measured by known processes immedi~
ately after the tubular film has emerged from the oven.
Alternatively, the thickness distribution around the tubular film can be measured when -the film has been collapsed. It is also possible to take a sample from the stretched tubular film for a measurement of the thickness distribution of the film around its periphery.
. .: . .
.,: . ... . - -:
.
: - : . , , ~3~ll3 The extruded and blow-forrned tubular film which has been collapsed can be re-inflated by known processes, e.g., by the processes described in Publi~hed German Application 22 63 623 and in German Patent Specifica-tion 31 19 006.
The inflation ratio can be contro]led to control the stretching ratio in the peripheral direction.
Biaxially stretched tubl~ar films will even be obtained if, in the process known from Published German Applica-tion 20 57 255, the tubular film is inflated to have a desired diameter when entering the oven and that diameter is kept constant during the travel through the oven.
The single figure of the drawing i8 a side elevation showing an extruding and blow-forming plant and a succeeding apparatus for stretching re-inflated tubular films in an oven.
~ ' Detailed Description of the Preferred Empodiment An illustrative embodiment of the invention ;
will now be described more in detail with reference to the drawing.
The extruding and blow-forming plant comprises a conventional extruder 1, which supplies molten synthetic thermoplastics to a film-blowing head 2J : .
which is also known. ~he blow head 2 is provided with blowing means for inflating the tubular film 4 and with known cooling rings 3. The tubular film 4 which has been extruded from the film-blowing head 2 ;
"
,. . .: ~ .: ,: . :, .. .. . . .. - : . : . ~ . .. :, .
: :, . : , ~ ; ., ::: :
- 6 - 2~3~
~nd has been in~lated move~ through sizing Mean~ 5 and is subsequently collap~ed b~; means of plate~ 6 and fla~ten-ing rol.lers 7. The thus collapsed tubu:Lar film ~ is then moved to squeeze rolls 9, possibly through an interposed holdlng mechanism, which i~ not ~hown but is known per se. The collapsed tubular film ~ is then re-inflated to form an inflated tubular film. '~he mean~ Eor inflating are of l~lown type and for ~his reason are not described in detail herein.
The inflated tubular film 10 passes through a heating oven 11 and is subsequently delivered via collapsing means to squeeze rolls 13. Said squeeze rolls 13 are succeeded by a take-up 14 for winding up the stretched tubular film at a velocity which i9 higher than the velocity at which the -film is .
fed to the squeeze rolls 9. It is apparent from the ~
drawing that a capacitive thicl~ness sensor 15 is ~ -provided closely behind the oven and comprises a revolving measuring head 16. ~he measured-value si~nals generated by that measuring head are delivered to a computer 17, which delivers signals to the several temperature-control segments in the blow head ~.
The control of the thickness distribution around the tubular film 10 entering the oven is pref-erably controlled by the process described in German Patent Specification 30 14 989, in which the measured thicknesses of the stretched film are converted to such a thickness distribution of the tubular film entering the oven that the stretched tubular film will have the desired uniform thickness distribution.
, .: : : . ....... .
, .
. ~
Claims
THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
A process of controlling the film thickness of a blow-formed and axially and preferably biaxially stretched tubular film, which when it has been formed in an extruding and blow-forming plant is collapsed and subsequently re-inflated to form an inflated tubular film or expanded to form a tubular film and in an inflated or expanded state is moved through an oven, from which the film is withdrawn and re-collapsed while moving at a velocity which is higher than the feeding speed in accordance with the desired stretching ratio, characterized in that the film thickness of the stretched tubular film which has emerged from the oven is measured around the tubular film before or after it has been collapsed and in dependence on the thus measured thicknesses of the peripheral profile the thickness distribution around the peripheral profile of the tubular film formed in the extruding and blow-forming plant is so controlled that any deviation from the average film thickness of the film which has been stretched in the oven, which deviation has been caused by a non-uniform heating of the film and possibly to other disturbing influences exerted on the film in the oven, will substantially be compensated.
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
A process of controlling the film thickness of a blow-formed and axially and preferably biaxially stretched tubular film, which when it has been formed in an extruding and blow-forming plant is collapsed and subsequently re-inflated to form an inflated tubular film or expanded to form a tubular film and in an inflated or expanded state is moved through an oven, from which the film is withdrawn and re-collapsed while moving at a velocity which is higher than the feeding speed in accordance with the desired stretching ratio, characterized in that the film thickness of the stretched tubular film which has emerged from the oven is measured around the tubular film before or after it has been collapsed and in dependence on the thus measured thicknesses of the peripheral profile the thickness distribution around the peripheral profile of the tubular film formed in the extruding and blow-forming plant is so controlled that any deviation from the average film thickness of the film which has been stretched in the oven, which deviation has been caused by a non-uniform heating of the film and possibly to other disturbing influences exerted on the film in the oven, will substantially be compensated.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3941185.0 | 1989-12-13 | ||
| DE3941185A DE3941185A1 (en) | 1989-12-13 | 1989-12-13 | METHOD FOR REGULATING THE FILM THICKNESS OF TUBE FILMS PRODUCED BY BLOW PROCESSING AND AXIAL, PREFERRED BIAXIAL |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2030843A1 true CA2030843A1 (en) | 1991-06-14 |
Family
ID=6395395
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002030843A Abandoned CA2030843A1 (en) | 1989-12-13 | 1990-11-26 | Process of controlling the film thickness of blow-formed and axially and preferably biaxially stretched tubular films |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0432423A1 (en) |
| JP (1) | JPH03189125A (en) |
| CA (1) | CA2030843A1 (en) |
| DE (1) | DE3941185A1 (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102009033171B4 (en) | 2009-07-13 | 2016-03-03 | Hosokawa Alpine Ag | Method for controlling the film thickness of stretched tubular films and apparatus for carrying out the method |
| JP5502639B2 (en) * | 2010-07-20 | 2014-05-28 | ホソカワ アルピーネ アクチエンゲゼルシャフト | Method for thickness control of stretched blown film |
| DE102013007669A1 (en) | 2013-05-02 | 2014-11-06 | Windmöller & Hölscher Kg | Method for controlling the thickness profile of inline stretched films |
| DE202013012785U1 (en) | 2013-07-19 | 2019-08-02 | Windmöller & Hölscher Kg | Device for producing inline stretched films |
| DE102013012134A1 (en) | 2013-07-19 | 2015-01-22 | Windmöller & Hölscher Kg | Device for producing inline stretched films |
| DE202013012786U1 (en) | 2013-07-19 | 2019-08-02 | Windmöller & Hölscher Kg | Device for producing inline stretched films |
| EP3057770B1 (en) | 2013-10-15 | 2021-09-08 | Reifenhäuser GmbH & Co. KG Maschinenfabrik | Method for producing a blown-film web, and blown-film installation |
| DE102016012469A1 (en) | 2016-10-18 | 2018-04-19 | Reifenhäuser GmbH & Co. KG Maschinenfabrik | Method and apparatus for determining a thickness distribution system of a doubly flattened film web, method for adjusting the film thickness profile of a doubled flattened film web, use of a method of adjusting a film thickness profile, and blown film equipment for producing a doubly flattened film web |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2658518C2 (en) * | 1976-12-23 | 1983-04-28 | Reifenhäuser KG, 5210 Troisdorf | Plant for the production of blown films made of thermoplastic material |
| DE2721609C2 (en) * | 1977-05-13 | 1986-07-10 | Reifenhäuser KG, 5210 Troisdorf | Control device for a plant for the production of blown plastic films |
| AU610366B2 (en) * | 1988-03-31 | 1991-05-16 | Idemitsu Petrochemical Co., Ltd. | Method of and apparatus for manufacturing biaxially oriented film |
-
1989
- 1989-12-13 DE DE3941185A patent/DE3941185A1/en not_active Withdrawn
-
1990
- 1990-10-25 EP EP90120516A patent/EP0432423A1/en not_active Withdrawn
- 1990-11-26 CA CA002030843A patent/CA2030843A1/en not_active Abandoned
- 1990-11-28 JP JP2328740A patent/JPH03189125A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03189125A (en) | 1991-08-19 |
| DE3941185A1 (en) | 1991-06-20 |
| EP0432423A1 (en) | 1991-06-19 |
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