The present invention relates to a lip gap adjusting device, an extrusion molding die, an extrusion molding apparatus, a method for adjusting lip gap, and a method for manufacturing a film.
There is known an extrusion molding die (T die) that extrudes a film-shaped molten resin from a space (a slit, a gap; hereinafter, referred to as a lip gap) between lips formed at a tip end (see Patent Literature 1, for example).
Patent Literature 1 discloses a plurality of heat bolts that are disposed in a width direction of an extrusion molding die in order to control the thickness of a film-shaped molten resin extruded from a lip gap to be uniform throughout an entire region in a width direction thereof. By manually rotating a lip adjusting screw, the heat bolts move in an axial direction thereof to push or pull one lip (a movable lip, a flexible lip), and locally adjust the lip gap. Thereby, the thickness of the film-shaped molten resin that is extruded from the lip gap thereafter is controlled to be uniform.
There is a room for improvement because it takes a considerable amount of time to manually rotate respective lip adjusting screws of a plurality of heat bolts one by one to adjust the lip gap.
The other problems and new features will become apparent from the description of the present specification and the accompanying drawings.
In a lip gap adjusting device according to one embodiment, a plurality of lip gap adjusting mechanisms disposed in a width direction of an extrusion molding die and configured to adjust a lip gap at respective disposition spots each include an actuator, and a coupling member configured to couple an output shaft of the actuator and a movable lip. The actuator adjusts the lip gap via the coupling member.
According to the one embodiment, it is possible to provide the lip gap adjusting device, the extrusion molding die, an extrusion molding apparatus, a method for adjusting a lip gap, and a method for manufacturing a film that can shorten a time period required for adjustment of the lip gap.
Hereinafter, specific embodiment will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiment. Further, in order to clarify the explanation, the following description and drawings are properly simplified.
First, an entire configuration of an extrusion molding apparatus 1 according to a first embodiment will be described with reference to
The extrusion molding apparatus 1 is an apparatus that extrudes a molten resin that is extruded from an extruder 10 (molten resin outlet 11) into a film form from a slit outlet formed at a tip end of a T die 20 (extrusion molding die), that is, a space (a slit, a gap; hereinafter, referred to as a lip gap) between lips. In the present specification, the film includes a sheet.
As shown in
The extruder 10 is a device that extrudes a resin that is heated and melted (hereinafter, referred to as a molten resin) from the molten resin outlet 11. The extruder 10 may be a screw type extruder, or may be a plunger type extruder.
The cooling roll 40 carries out a film 93 resulting from solidification of a film-shaped molten resin 92a while cooling the film-shaped molten resin 92a extruded from the T die 20. The film 93 that is carried out from the cooling roll 40 is conveyed via the conveyor roll group 50, and is wound up by the winder 60. In an example of
The thickness sensor 70 is an online thickness sensor (thickness gauge), and measures thickness of the film formed from the molten resin extruded from the T die 20 in real time at a plurality of positions (at least a plurality of positions corresponding to a plurality of lip gap adjusting mechanisms 31 disposed as described later) along a width direction of the T die 20 (direction orthogonal to a paper surface in
The lip gap measuring unit 71 measures a lip gap at a plurality of positions along the width direction of the T die 20 (a plurality of positions corresponding to the plurality of lip gap adjusting mechanisms 31 that are disposed as described later). A lip gap at each of the plurality of positions may be detected by applying predetermined image processing to an image including the lip gap captured by a camera, or may be detected by a laser type gap sensor. Note that the lip gap at each of the plurality of positions may be manually measured by using a gap gauge. Note that, in the case of manual measurement, it is necessary to input measurement data to the control unit 80 manually.
The control unit 80 controls an actuator so that the thickness of a film becomes uniform based on the thickness (thickness data) of the film measured at the plurality of positions by the thickness sensor 70. The control unit 80 includes a processor though not illustrated. The processor is, for example, a CPU (Central Processing Unit). An operation of the control unit 80 will be described later.
Next, a configuration of the T die 20 will be described with reference to
The T die 20 is a block-shaped member that molds the molten resin extruded from the extruder 10 into a film form. The T die 20 is typically made of a metal.
As shown in
The T die 20 includes a pair of die blocks 21 and 22. The die block 21 is one example of a first die block of the present invention, and the die block 22 is an example of a second die block of the present invention. The pair of die blocks 21 and 22 respectively include surfaces 21a and 22a that face each other. Though not illustrated, the T die 20 includes an introduction passage, a manifold, and a slit 23c that are formed between the surfaces 21a and 22a facing each other.
The introduction passage is a passage that allows the base end portion 20b of the T die 20 to which the extruder 10 is connected, and the manifold to communicate with each other. The introduction passage extends from the base end portion 20b of the T die 20 toward the tip end portion 20a on an opposite side thereof. A molten resin that is extruded from the extruder 10 is introduced into the introduction passage.
The manifold is a passage extending in the width direction (direction orthogonal to a paper surface in
The slit 23c is a gap that allows the tip end portion 20a of the T die 20 and the manifold to communicate with each other. The slit 23c extends in the width direction of the T die 20.
A pair of die blocks 21 and 22 respectively include tip end portions including taper surfaces 21b and 22b that are inclined toward tip ends. The die block 21 includes a movable lip 21c (flexible lip). The movable lip 21c can locally displace with a bottom portion of a recessed portion 21d formed at the tip end portion of the die block 21 as a support point by being pushed or pulled by a lip gap adjusting mechanism 31 described later. A tip end (lower end in
On the other hand, the die block 22 includes a fixed lip 22c. The fixed lip 22c is one example of a mating lip of the present invention. The fixed lip 22c does not displace even when the movable lip 21c is pushed or pulled by the lip gap adjusting mechanism 31 described later. A tip end (lower end in
In the T die 20 of the above-described configuration, the molten resin extruded from the extruder 10 passes through the introduction passage and the manifold that are provided inside of the T die 20, in this order. At this time, the molten resin is pushed and spread in the width direction of the T die 20 by passing through the manifold. The molten resin that is pushed and spread in the width direction of the T die 20 passes through the slit 23c, and is finally extruded into a film form from a slit outlet formed at a tip end of the T die 20, that is, a lip gap S between the movable lip 21c and the fixed lip 22c. A width of the molten resin 92a (see
The first embodiment is characterized by including a lip gap adjusting device 30 that will be described below.
As shown in
The actuator 311 includes an actuator body 311a, and the output shaft 311b that is a rotary shaft. The actuator 311 is, for example, a servomotor (a DC servomotor, an AC servomotor), a stepping motor, a coreless motor, or a DD motor.
The coupling member 312 is a rod member (or an adjusting bolt; hereinafter, referred to as a rod member 32) in which a tip end portion is screwed into the movable lip 21c, and a base end portion is coupled (fixed) to the output shaft 311b of the actuator 311. The rod member 32 is typically made of a metal.
As shown in
The control unit 80 is electrically connected to the actuator 311. The control unit 80 controls a rotation direction (a forward direction or a reverse direction) and a rotation amount of the output shaft 311b as described later. The actuator 311 follows control of the control unit 80, and rotates the output shaft 311b (and the rod member 32) to change a screwing amount of the rod member 32 into the movable lip 21c. Thereby, the movable lip 21c displaces (is pushed or pulled) with respect to the fixed lip 22c, and the lip gap S is adjusted.
In order to make the thickness of the film-shaped molten resin extruded from the lip gap S uniform throughout an entire region in the width direction of the T die 20, the plurality of lip gap adjusting mechanisms 31 are attached to the T die 20 (die block 21) in the width direction thereof as shown in
Next, an operation example of the lip gap adjusting mechanism 31 of the above-described configuration will be described.
According to the lip gap adjusting mechanism 31 of the above-described configuration, it is possible to locally adjust the lip gap S by controlling the rotation direction (the forward direction or the reverse direction) and the rotation amount of the output shaft 311b (and the rod member 32).
For example, the output shaft 311b (and the rod member 32) is rotated (for example, rotated forward) by the actuator 311 to change (decrease) the screwing amount of the rod member 32 into the movable lip 21c. Thereby, the movable lip 21c locally displaces with the bottom portion of the recessed portion 21d as the support point to move close to the fixed lip 22c. Thereby, the lip gap S is locally narrowed. As a result, the thickness of the film-shaped molten resin (film 93) that is thereafter extruded from the lip gap S locally decreases.
Conversely, the output shaft 311b (and the rod member 32) is rotated (for example, reversely rotated) by the actuator 311 to change (increase) the screwing amount of the rod member 32 into the movable lip 21c. Thereby, the movable lip 21c locally displaces with the bottom portion of the recessed portion 21d as the support point and separates from the fixed lip 22c. Thereby, the lip gap S is locally widened. As a result, the thickness of the film-shaped molten resin (film 93) that is thereafter extruded from the lip gap S locally increases.
Next, an operation example of the lip gap adjusting device 30 of the above-described configuration (before start of molding) will be described. As described below, by adjusting the lip gap at each of the plurality of positions uniformly before start of molding, it is possible to quickly adjust the thickness of the film-shaped molten resin (film 93) that is extruded from the lip gap S uniformly after start of molding.
The following process is realized by the control unit 80 (processor) executing a program that is loaded into a memory (not illustrated) such as a RAM (Random Access Memory) from a storage device (not illustrated) such as a hard disk drive.
When temperature rising of the T die 20 is completed (step S10), the lip gap measuring unit 71 measures the lip gap (lip space) (step S11). Specifically, the lip gap measuring unit 71 measures the lip gap (lip space) at the plurality of positions (plurality of positions corresponding to the plurality of lip gap adjusting mechanisms 31) along the width direction of the T die 20. The measured lip gaps (gap data) are transferred to the control unit 80.
Next, when the lip gaps (plural) measured in step S11 are not uniform (step S12: No), for example, when a lip gap measured in at least one position is outside an allowable range, the control unit 80 performs a control analysis (step S13), and controls the actuator 311 of the lip gap adjusting mechanism 31 corresponding to the position at which the lip gap outside the allowable range is measured (step S14).
Specifically, the control unit 80 locally adjusts the lip gap by controlling the actuator 311 (the rotation direction and the rotation amount of the output shaft 311b) of the lip gap adjusting mechanism 31 corresponding to the position at which the lip gap outside the allowable range is measured so that the lip gaps become uniform (for example, so that the lip gap outside the allowable range is within the allowable range), based on the lip gaps (gap data) measured in step S11.
Next, the lip gap measuring unit 71 measures the lip gaps (lip spaces) again (step S11).
Thereafter, until the lip gaps (plural) measured in step S11 become uniform, the processes in steps S13, S14, and S11 described above are repeatedly executed (step S12: No).
On the other hand, when the lip gaps (plural) measured in step S11 become uniform (step S12: Yes), that is, when all the lip gaps respectively measured at the plurality of positions are within the allowable range, molding is started (step S15).
Next, an operation example of the lip gap adjusting device 30 of the above-described configuration (after start of molding) will be described.
The following process is realized by the control unit 80 (processor) executing a program loaded into a memory (not illustrated) such as a RAM (Random Access Memory) from a storage device (not illustrated) such as a hard disk drive.
After start of molding (step S20), that is, while the film-shaped molten resin is extruded from the lip gap S, the thickness sensor 70 measures the thickness of the film formed from the molten resin extruded from the T die 20 (lip gap S) (step S21). Specifically, the thickness sensor 70 measures the thickness of the film in real time at a plurality of positions (plurality of positions corresponding to the plurality of lip gap adjusting mechanisms 31) along the width direction of the T die 20. The thickness of the film that is measured (thickness data) is transferred to the control unit 80.
Next, when the thicknesses (plural) of the film measured in step S21 is not uniform (step S22: No), for example, when the thickness of the film measured in at least one position is outside an allowable range, the control unit 80 performs a control analysis (step S23), and controls the actuator 311 of the lip gap adjusting mechanism 31 corresponding to the position at which the thickness of the film outside the allowable range is measured (step S24).
Specifically, the control unit 80 locally adjusts the lip gap by controlling the actuator 311 (the rotation direction and the rotation amount of the output shaft 311b) of the lip gap adjusting mechanism 31 corresponding to the position at which the thickness of the film outside the allowable range is measured so that the thickness of the film becomes uniform (for example, so that the thickness of the film outside the allowable range is within the allowable range), based on the thicknesses of the film measured in step S21 (thickness data).
Next, the thickness sensor 70 measures the thickness of the film formed from the molten resin extruded from the T die 20 (lip gap) again (step S21).
Thereafter, until the thicknesses (plural) of the film measured in step S21 become uniform, the processes of steps S23, S24 and S21 described above are repeatedly executed (step S22: No).
On the other hand, when the thicknesses (plural) of the film measured in step S21 become uniform (step S22: Yes), that is, all the thicknesses of the film measured at the respective plurality of positions are within the allowable range, adjustment is completed (step S25). As above, the film with a uniform thickness can be manufactured.
Next, a relationship between a time period and a displacement amount of the movable lip 21c when the lip gap S is adjusted by the lip gap adjusting device 30 of the above-described configuration will be described.
Referring to
Next, a comparative example will be described.
As shown in
Referring to
As above, it is found that when the lip gap S is adjusted by the lip gap adjusting device 30 (the actuator 311 and the rod member 32), a time period required to displace to a target value is overwhelmingly short (the lip gap S can be adjusted extremely quickly), as compared with the case of adjusting the lip gap S by the lip gap adjusting device 130 (heat bolt 33).
As described above, according to the first embodiment, it is possible to shorten the time period required for adjustment of the lip gap.
This is because the actuator 311 and the rod member 32 are used instead of the heat bolt, as the lip gap adjusting mechanism 31, and the actuator 311 rotates the rod member 32 to change the screwing amount of the rod member 32 into the movable lip 21c, and thereby adjusts the lip gap S.
Further, according to the first embodiment, by attaching the actuators 311 to the coupling members 312 (rod members or adjusting bolts) one by one, all the coupling members 312 (the rod members or the adjusting bolts) can be simultaneously pushed and pulled at a rough adjustment stage (before start of molding), whereas at a fine adjustment stage (after start of molding), the time period required to reach the target displacement amount is overwhelmingly shorter than the heat bolt, so that it is possible to shorten the time period required for thickness control of the film.
Further, according to the first embodiment, there is also an advantage that there is no risk of damage to the coupling member 312 (the rod member or the adjusting bolt) due to excessive tightening because the lip gap is adjusted by only the actuator 311, although when adjustment (rough adjustment) of the lip gap by bolt tightening is manually performed, there is a risk that the heat bolt may be damaged by being bent or the like by excessive tightening.
Further, according to the first embodiment, there is no need for manual adjustment by performing control with the actuator 311, and therefore, there is also an advantage that there is no need to approach the T die 20 which is a hot object, and a roll (cooling roll 40 or the like) which is a rotating body and perform operations during molding (increase in safety).
Next, modified examples will be described.
In the first embodiment described above, the example using the rod member 32 as the coupling member 312 that couples the output shaft 311b of the actuator 311 and the movable lip 21c to each other is described, but the present invention is not limited to this.
For example, as shown in
The differential screw 34 is a differential screw in which a pitch of an external screw 341 and a pitch of an internal screw 342 are different (the pitch of the external screw 341>the pitch of the internal screw 342).
The external screw 341 of the differential screw 34 is screwed into a holding portion 21j provided at a die block 21. A rod 343 is screwed onto the internal screw 342 of the differential screw 34. The tip end portion of the differential screw 34 (rod 343) is coupled (fixed) to the movable lip 21c. Note that a center axis AX311b (rotation axis) of the output shaft 311b of the actuator 311 and a center axis AX34 (rotation axis) of the differential screw 34 coincide (substantially coincide) with each other.
According to modified example 1, it is possible to exhibit similar effects to those of the first embodiment, such as being able to shorten the time period required for adjustment of the lip gap.
This is because the actuator 311 and the differential screw 34 are used as the lip gap adjusting mechanism 31 instead of the heat bolt, and the actuator 311 rotates the differential screw 34, and thereby adjusts the lip gap S.
In the first embodiment described above, the example using the actuator 311 including the actuator body 311a, and the output shaft 311b that is a rotary shaft is described, but the present invention is not limited to this.
For example, as shown in
According to modified example 2, it is also possible to exhibit similar effects to those of the first embodiment, such as being able to shorten the time period required for adjustment of the lip gap.
This is because the actuator 313 and the rod member 35 are used as the lip gap adjusting mechanism 31 instead of the heat bolt, and the actuator 313 extrudes or retracts the output shaft 313b, and thereby adjusts the lip gap S.
As shown in
The first lip gap adjusting mechanism 31A includes an actuator 311 (hereinafter, referred to as a first actuator 311A), and a coupling member 312 (hereinafter, referred to as a first coupling member 312A) that couples an output shaft 311b of the first actuator 311A and a movable lip 21c.
The second lip gap adjusting mechanism 31B includes an actuator 311 (hereinafter, referred to as a second actuator 311B), and a coupling member 312 (hereinafter, referred to as a second coupling member 312B) that couples an output shaft 311b of the second actuator 311B and the movable lip 21c.
The first actuator 311A is disposed close to the movable lip 21c. A length in an axial direction of the first coupling member 312A that couples the output shaft 311b of the first actuator 311A and the movable lip 21c is L1.
On the other hand, the second actuator 311B is disposed far from the movable lip 21c so as not to interfere with the first actuator 311A. A length in an axial direction of the second coupling member 312B that couples the output shaft 311b of the second actuator 311B and the movable lip 21c is L2 that is longer than L2.
According to modified example 3, it is also possible to exhibit similar effects to those of the first embodiment, such as being able to shorten the time period required for adjustment of the lip gap. Further, according to modified example 3, as compared with the first embodiment described above, a disposition interval L3 of the coupling members 312 can be narrowed (the disposition interval L3 shown in
In the first embodiment described above, the example of using the T die 20 including the die block 21 including the movable lip 21c and the die block 22 including the fixed lip 22c as the extrusion molding die is described, but the present invention is not limited to this.
For example, as shown in
The first die block 21A includes a plurality of third lip gap adjusting mechanisms 31A that are disposed in a width direction (direction orthogonal to a paper surface in
According to modified example 4, it is also possible to exhibit similar effects to those of the first embodiment.
Note that in each of the T die 20 of modified example 1 (see
The invention made by the present inventor is specifically described based on the embodiment thus far, but it goes without saying that the present invention is not limited to the embodiment already described, and various changes can be made within the range without departing from the gist of the invention.
Filing Document | Filing Date | Country | Kind |
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PCT/JP2021/010695 | 3/16/2021 | WO |