JPH0746505Y2 - Inflation film forming equipment - Google Patents

Description

[Detailed Description of Device] a. Purpose of the Invention (Field of Industrial Application) The present invention relates to a device for forming an inflation film in which the frost line is automatically adjusted in accordance with the blow ratio.

<Prior Art> An example of this type of method is described in JP-A-58-78725.

As a method of adjusting the frost line described in the above publication,
The air flow control valve of the cold air system is used. There is a risk that the frost line will not stabilize at a certain height and will constantly fluctuate greatly if the air flow rate adjusting valve of this device alone is adjusted, and the adjustment of the frost line is unstable.

Further, in the air ring of the individual seed molding device, a film having a predetermined thickness and a predetermined strength can be molded when the production speed of the film is slow and the cooling air amount is small, but the speed of the film (particularly high density polyethylene) is high. In the case of an ultra-thin film (about 10 microns) or when forming a film of about 20 microns used for a synthetic resin shopping bag at a medium speed, the cooling air amount must be increased. As a result, the bubbles oscillate and the wall thickness becomes uneven.

In order to reduce such fluctuations, various inflation film forming apparatuses have been developed in which molten bubbles extruded from the annular discharge port of the forming die are supported by at least two upper and lower bubble internal stabilizers from the inside thereof. All of them have a feeling that they are just one step away from forming a film with a well-balanced strength in the MD direction (bubble take-up direction) and the TD direction (direction perpendicular to this take-up direction).

Further, during the molding, air is entrained upward between the two-stage bubble internal stabilizers as the bubbles are taken in,
The internal pressure between the bubble internal stabilizers tends to be reduced, and the bubble locally shrinks in this part, and a film having the desired strength is not formed. There is a risk that the bubbles will break due to the close contact with.

(Problems to be Solved by the Invention) This invention improves the above-mentioned drawbacks and automatically adjusts the frost line to a predetermined height to stabilize it without much fluctuation, and also has the strength balance in both MD and TD directions. A film, particularly an ultrathin film and a film of about 20 microns can be formed by the same forming apparatus, and an apparatus for reducing the tendency of the internal pressure between the two-stage bubble internal stabilizers to be reduced is provided to the market. To aim.

B. Configuration of the Invention (Means for Solving the Problems) In order to solve the above-mentioned problems, this invention proposes that at least the upper and lower portions of a molten bubble extruded from an annular discharge port of a molding die are attached to an internal air blowing pipe. It is supported from the inside by a two-stage bubble internal stabilizer, and the bubbles are cooled from the outer peripheral surface by the cool air blown from the bubble cooling ring provided near the annular discharge port, and this bubble is desired on the downstream side of the downstream bubble internal stabilizer. The inflation film having a predetermined width is formed by expanding the diameter, and the vertical movement of the expansion start point of the bubble is detected by at least two sets of upper and lower non-contact detection devices. When the rise of the expansion start point is detected, the air ring The cooling air discharge rate is increased, and when the decrease is detected, this cooling air discharge rate is decreased and the frost line is adjusted according to the blow ratio. In an inflation film forming apparatus that dynamically adjusts, the most upstream bubble internal stabilizer near the forming die has a bubble guiding cylinder portion having a diameter approximately equal to the diameter of the annular discharge port, and a downstream side of this cylinder portion. It is composed of a tapered frustoconical bubble guide portion whose downstream side is smaller in diameter than the upstream side, and is located at a position where the cool air is blown toward the peripheral surface of the tapered bubble guide portion in the upstream bubble internal stabilizer. ,
The annular cold air outlet of the bubble cooling ring is open, the upstream maximum diameter of the tapered bubble guide portion matches the diameter of the cylindrical body portion, and the downstream bubble internal stabilizer is a hollow body. In addition, the diameter of the downstream end is formed to be smaller than the minimum diameter of the tapered bubble guide portion in the upstream bubble internal stabilizer, and the outer diameter of the downstream bubble internal stabilizer gradually increases toward the downstream side. Moreover, the hollow portion of the downstream bubble internal stabilizer is communicated with the outside through the communication holes provided in the upper and lower end plates, respectively.
The upstream bubble internal stabilizer is provided with a communication hole that penetrates vertically, and further, a machine frame near the expansion start point of the synthetic resin tube of the apparatus for manufacturing a film by the inflation method or a member integrated therewith. In addition, two sets of non-contact detection devices are provided above and below to detect the presence or absence of the film at the expansion start portion,
Depending on the presence or absence of these detection signals, the increase or decrease of the cooling air discharge amount from the air ring surrounding the tube is provided in the speed change of the blower rotation variable speed motor of the air ring or a part of the air system of the air ring. If the state of the output signal of the up-and-down detection device does not change from the previous detection state after the decrease or increase of the air discharge amount is continued for a predetermined time, the control unit is provided by adjusting the opening degree of the damper. In addition, an inflation film forming apparatus is provided with an automatic adjusting device configured to further reduce or increase the air discharge amount further and adjust the frost line to stabilize the frost line at a constant height.

In order to solve the above-mentioned problems, the downstream side bubble internal stabilizer of the inflation film forming apparatus of the present invention comprises:
It is preferable that at least three cylindrical portions having different diameters are stacked and the diameter is increased toward the downstream side.

(Operation of the Invention) The operation of the inflation film forming apparatus of the present invention configured as described above is as follows.

First, the molten bubble extruded from the annular discharge port of the molding die is expansion-molded on the peripheral surface of the bubble guiding cylinder portion to a diameter slightly larger than the diameter of the annular discharge port of the molding die to reduce its wall thickness. In the state where the heat transfer area is increased by this, this bubble is brought into contact with the tapered bubble guide part peripheral surface by the air blown from the annular cold air blowing port of the cooling ring, and is contracted in the radial direction to the downstream side. By being expanded and contracted, the bubbles are stretch-molded in the TD direction by an amount commensurate with the MD orientation, and contact or non-contact with a part of the downstream-side bubble internal stabilizer depending on the molding speed on the downstream side. To reduce slightly in the radial direction.

Thus, the bubble repeatedly subjected to expansion and contraction is expanded at a neck-in position in the radial direction at a stretch and stretch-formed in the MD direction to manufacture a film having a balanced strength in both MD and TD directions.

At the time of manufacturing such a film, the vertical movement of the expansion start point of the bubble is detected by at least two upper and lower non-contact detection devices, and when the rise of the expansion start point is detected, the cooling air discharge amount of the air ring is increased. In addition, when the lowering is detected, the discharge amount of the cooling air is reduced and the frost line is automatically adjusted according to the blow ratio.

At this time, if the state of the output signal of the up / down detection device does not change from the previous detection state after the decrease or increase of the air discharge amount is continued for a predetermined time, this air discharge amount is changed stepwise as in the previous time. Further, the frost line is further reduced or increased to adjust the frost line to stabilize at a constant height. The control unit for adjusting the discharge air amount includes two detection devices arranged vertically and at intervals of 1 to 15 seconds. It is composed of a pulse transmitting device for transmitting one pulse and a step-progressive-regression level changing device, and the step-progressing-regressive level changing device is provided with three ON-signals of the two detecting devices and the pulse transmitting device. A model that advances one step from the previous expression level, one step back from the previous expression level by the OFF signal of the two detection devices and the ON signal of the pulse transmission device, and is inoperative with other signals There as things.

As described above, as the film is formed at a high speed and is taken up by a winder or the like, a part of the air flow inside the bubble is accompanied with the film flow, and the upstream bubble internal stabilizer and the downstream bubble internal stabilizer are formed. Taking the tendency to reduce the pressure in the annular space located in the middle of the, and by the air that has flowed into the downstream side of the downstream bubble internal stabilizer, the pressure increase in the downstream side of the downstream bubble internal stabilizer The air that has become slightly higher in pressure on the downstream side of the downstream bubble internal stabilizer for a short period of time temporarily flows between the upper and lower two stages of bubble internal stabilizers and the inside of the upstream bubble via the communication hole. Rings flow into each annular space on the upstream side of the stabilizer, and the pressure in these spaces is returned to the original value within the range of slight fluctuations. Stretching to,
Also, it prevents the bubble forming diameter from increasing and prevents its breakage.

Further, since the downstream-side bubble internal stabilizer has an overall truncated conical truncated cone shape having a larger diameter on the downstream side, the downstream-side bubble of the overall inverted truncated cone shape is formed in the stabilizer in accordance with the forming speed of the film. A part of the outer surface of the reverse taper of the inner stabilizer 13 is contacted or not contacted with the inner stabilizer 13 and is slightly reduced in the radial direction. That is,
As the take-up speed increases, the position where the bubble comes into contact with the reverse taper outer peripheral surface of the downstream bubble internal stabilizer moves to the upstream side with a small diameter, and when the take-up speed exceeds 120 m / min, this downstream bubble The bubbles will be taken away from the reverse tapered outer peripheral surface of the internal stabilizer.

The bubble that has been repeatedly expanded and contracted in this way is expanded in the radial direction at the neck-in position at a stretch and stretch-formed in the TD direction to produce a film F having a balanced strength in both MD and TD.

In the device according to claim 2, the downstream bubble internal stabilizer is formed by stacking at least three cylindrical parts having different diameters, and has a larger diameter toward the downstream side. In addition, when the film forming speed is slow, a bubble in a melted state comes into contact with the outer peripheral surface of the cylindrical portion on the downstream end side that has the maximum outer diameter, necks in at this position, and the bubble bursts in the radial direction at a stretch. Expansion molded. On the contrary, when the film forming speed is increased, the contact position of the bubble with the outer periphery of the bubble internal stabilizer on the downstream side is in the middle cylindrical portion,
The bubbles gradually move to the cylindrical portion on the upstream end side having the minimum outer diameter, and the bubbles come into contact with the downstream bubble internal stabilizer at a position corresponding to the forming speed of the film F, that is, at an optimum height from the forming die. Then, the contact position is set as the neck-in position, and stretch molding is performed in the radial direction.

In addition, since there is no change in diameter within each cylinder,
Even if the contact position of the bubble moves up and down to some extent, it does not directly affect the bubble molding size.

(Example) A typical example of the present invention will be described below.

(Embodiment 1) This is a typical embodiment of the invention described in claim 1.

In FIG. 1, C is a control unit of the automatic adjustment device, and as the control unit C, two detection devices 2 arranged above and below,
3, a pulse transmission device 5 that emits one pulse at intervals of 1 to 15 seconds, a step change type level changing device 6, and an electric signal corresponding to the level expressed by the level changing device 6. It comprises a D / A conversion circuit 7 for converting into a quantity, and a variable speed motor 10 for driving the blower 9 of the air ring 8 is provided corresponding to the output of the D / A conversion circuit 7.

As shown in the figure, the above-mentioned detecting devices 2 and 3 are arranged such that, prior to the molding of the tube 1, a light beam is positioned above and below the desired expansion starting portion (stretching starting portion) 1a and in the tangential direction of this expansion starting portion 1a Light projectors 2a and 3a so that a and b pass horizontally
And the photodetectors 2b and 3b are one block, and the reflection type photoelectric detection devices 2 and 3 and the common reflection mirror 4 are arranged to face each other, and two sets of non-contact type photoelectric detection devices 2 are provided. 3 are provided on the machine frame of the film forming apparatus or a member integrated with the machine frame in the upper and lower layers.

As the pulse transmission device 5, a computer for normal control has been adopted in this type of molding machine in recent years, and the pulse transmission function in the computer can be used to adjust the pulse interval to any desired interval of 1 to 15 seconds. The pulse transmission device 5 of this application is used to generate pulses at intervals of 3 to 5 seconds.

A device other than a computer, such as a cycle counter, which transmits each time a predetermined number of external synchronization signals are transmitted, or a device which is reset and transmitted every time the timer times out, may be used.

The step progress / regression type level change device 16 is one that advances one step each time there is a one-shot step input signal, and regresses in one step each time there is a one-shot step input signal. It can be mechanical, electrical or electronic. The one shown in the figure is a digital display device, and the number of digital display is incremented by 1 every time there is a step-by-step one-shot input signal, while the number of display is 1 by every step-back-one-shot input signal. And there is no input,
Keep the same value. This digital number is the same as the present invention if it can be held as a value of information or a value of an electric signal that is invisible even if it is actually visible, and this digital display device can also utilize the digital display function of a computer. preferable.

Therefore, as the D / A conversion circuit 7 for converting the output of the level changing device 6 into an electric quantity, one which is normally output as a voltage change of 5 V or 10 V or less is used, and this output is used as an input for the variable speed motor 10. It is given to the control circuit 10a to change the speed of the variable speed motor 10.

The D / A conversion circuit can be omitted if the level changing device 6 is changed by an electric amount.

The control circuit 10a described above differs depending on the type of the variable speed motor 10 described above. For example, if it is a DC motor, it is a variable pressure device, or if it changes speed due to frequency change, it is a variable frequency converter.

Using such a control unit C, the frost line of the bubble is adjusted as follows.

First, as described above, the detection devices 2 and 3 are arranged vertically, and the positions and the air volume discharged from the air ring 8 are empirically determined to be approximately appropriate amounts, and the speed of the variable speed motor 10 at this time is determined. It is designed in advance so as to have a value near the middle of the variable speed range, and the digital number as the level changing device 6 at this time is, for example, 000.

In this way, the inflation molding is continued, and the expansion start position of the synthetic resin tube 1 being molded is higher than the positions of the two detection devices 2 and 3, and the two detection devices 2 and 3 are both light emitting elements. Light beams from 2a and 3a are light receiving elements 2b,
When 3b is reached and both emit ON signals, and the pulse transmission signal position 5 transmits, a one-shot input signal is given to the digital number display device 6, and this digital number becomes 001.

Using this changed digital number as an input, the D / A conversion circuit 7
Causes the input voltage of the motor 10 to increase by one step, the variable speed motor 10 rotates one step higher speed, the blower 9 rotates one step higher speed, and the air volume from the air cylinder 8 also increases one step, so that the tube being formed has the previous digital value. The expansion start position 1a of the tube 1 during molding is gradually lowered as compared with the case of 000.

In this way, when the upper detecting device 2 is turned off and the lower detecting device 3 is in a state of outputting an on signal, even if the next pulse transmitting device 5 outputs an output signal, the step change type level changing device 6 Since no input is given to, the state of 001 is maintained and the rotation speed of the blower 9 is maintained in the state of 001.

While the operation is further continued, the expansion start position 1a of the tube gradually lowers, and the lower detector 3 also outputs an off signal together with the upper detector 2, and the AND signal with the pulse of the pulse transmitter 5 causes When the step change input signal is given to the level changing device 6, it returns from the state of 001 to the state of 000 again, the variable speed motor 10 is decelerated by one step, and the expansion start position of the tube starts to rise again.

The level changing device 6 advances one step if the above-described two upper and lower detecting devices 2 and 3 are both turned on, and the level changing device 6 steps down one step when both the detecting devices 2 and 3 are both turned off. The motor 10 is shifted correspondingly.

Next, after the above-mentioned detection devices 2 and 3 are both turned on, the state is changed from 000 to 001, and when a predetermined time elapses, that is, when the pulse transmission device 5 transmits the next pulse, the detection device 2, When both 3 are still in the ON state, the level change device 6 is further given an input to the level change device 6 and advances one step from the 001 state to the 002 state.

Even with this, when the upper detection device 2 still does not output the off signal, the step further advances by one step, and the number of rotations of the variable speed motor 10 is correspondingly accelerated.

Similarly, it is assumed that the state when the expansion start position 1a is lowered is the state of 001, and even when the pulse transmission device 5 transmits the next pulse, the upper and lower two detection chambers 2 and 3 both emit the OFF signal. For example, the level change device 6 is the input for further stepping.
, The variable speed motor 10 further decreases in speed by one step, and the expansion start position 1a of the tube 1 is still reduced.
When does not rise, the expansion start position 1a rises every time the pulse transmission device 5 emits a pulse, and the lower detection device 3
Variable speed motor 10
Will be slow.

In the above-described embodiment, the air volume discharged by the air ring 8 is adjusted by controlling the rotation speed of the variable speed motor 10 that drives the blower 9. However, the damper provided in a part of the air system of the air ring 8 is opened. Even the method and apparatus for adjusting the degree stepwise are the same as the method and apparatus invention of this application.

The detection devices 2 and 3 are mounted on a numerically controlled XY table or the like for the optimum expansion start portion 1a which is displaced according to the change of the blow ratio of the tube 1.
It is convenient to make it possible to change the installation position of and to adjust the positions of the detection devices 2 and 3 according to various blow ratios of the tube 1.

Further, in FIG. 4, A shows a device for inflation-molding an ultrathin film F of about 10 microns at a high speed, and the movement adjusting device is incorporated therein.

At the center of the molding die 11 of this device A, an internal air blowing tube
20 are planted, an air exhaust passage 21 is provided, and an internal air circulation system is formed. Concentrically with the internal air blowing pipe 20, an upstream bubble internal stabilizer 12 and a downstream bubble internal stabilizer 13 are arranged in two steps in the upper and lower sides, with an annular space 23 between the bubble internal stabilizers 12, 13. Are formed.

The upstream bubble internal stabilizer 12 has a bubble guiding cylindrical body portion 12a having an outer diameter D substantially equal to the diameter d of the annular discharge port 14 of the molding die 11 and a downstream side of the bubble guiding cylindrical body portion 12a. It is composed of a continuous taper-shaped bubble guide portion 12b.

The tapered bubble guide portion 12b is in the shape of a truncated cone as a whole, and its outer diameter is equal to the outer diameter D of the bubble guide cylindrical portion 12a on the upstream side and smaller than the downstream side on the upstream side. The taper angle is preferably 3 to 5 degrees, but the invention is not limited to this value.

The downstream bubble internal stabilizer 13 has an overall inverted truncated cone shape, that is, a cone shape, and the outer diameter D ₀ of its upper end (downstream end) is smaller than the outer diameter d 1 of the upper end (downstream end) of the bubble guide portion 12b. The diameter is smaller toward the lower end (upstream end), that is, the outer diameter D _{1 of the} lower end is smaller than the outer diameter d ₁ and the outer peripheral surface thereof is inversely tapered.

An annular cold air outlet 16 of the bubble cooling ring 15 is opened at a position where the cool air is blown toward the tapered peripheral surface of the tapered bubble guide portion 12b, and the annular air leading to the cold air outlet 16 of the bubble cooling ring 15 is formed. The cold air blowing passage 17 has a diameter that becomes smaller toward the cold air blowing outlet 16, and is formed in a cone-shaped cylindrical cold air blowing passage inclined toward the downstream side, and the blowing direction thereof is the tapered bubble guide portion 12b. It is directed toward the taper peripheral surface.

The gap dimension t of the cold air blowing passage 17, that is, the cross-sectional area of the flow passage, becomes narrower toward the annular cold air blowing outlet 16.

The downstream-side bubble internal stabilizer 13 is entirely hollow,
The hollow portion 28 of the downstream-side bubble internal stabilizer 13 communicates with the outside through the communication holes 24 provided in the upper and lower end plates 26 and 27, respectively. A communication hole 25 penetrating therethrough is provided (operation of the first embodiment). The operation of this embodiment configured as described above is as follows.

The melted bubble B extruded from the annular discharge port 14 of the molding die 11 is expansion-molded on the peripheral surface of the bubble guiding cylinder portion 12a to a diameter slightly larger than the diameter d of the annular discharge port 14 of the molding die. In the state where the wall thickness is reduced and the heat transfer area is increased, the bubble B is blown by the air blown from the annular cold air blowout port 16 of the cooling ring 15 into the bubble guide portion 12
The bubble B is brought into contact with the tapered peripheral surface of b and is contracted in the radial direction, and is drawn to the downstream side. By receiving this expansion and contraction, the bubble B is stretch-molded in the MD direction by an amount commensurate with the TD orientation. Then, on the downstream side, depending on the forming speed of the film F, it is slightly or radially reduced in contact or non-contact with a part of the reverse taper outer peripheral surface of the downstream-side bubble internal stabilizer 13 having the entire inverted truncated cone shape. More specifically, as the take-up speed increases, the position at which the bubble B contacts the reverse taper outer peripheral surface of the downstream bubble internal stabilizer 13 moves to the small diameter upstream side, and the take-up speed increases. If it exceeds 120 m / min, the bubbles will be taken away from the reverse taper outer peripheral surface of the downstream side bubble internal stabilizer 13 in a separated state.

The bubble B, which has been repeatedly expanded and contracted in this way, is expanded in the radial direction at a neck-in position and stretch-molded in the TD direction to produce a film F having a balanced strength in both MD and TD.

As described above, as the film is formed at a high speed and taken up by the winder, a part of the air flow inside the bubble is accompanied by the film flow, and the upstream bubble internal stabilizer 12 and the downstream bubble internal stabilization The pressure in the annular space 23 located in the middle of the body 13 is reduced, and the internal pressure tends to increase on the downstream side of the downstream bubble stabilizer, but each of the bubble internal stabilizers 12,
Since the communication holes 24 and 25 are provided in the air passage 13, the air rising from between the bubble B and each stabilizer flows into the annular space 23 again through the communication holes 24 and 25 due to the pressure difference between them. The pressure inside this space 23 is returned to its original value, and the upper and lower bubble internal stabilizers 12,
The internal pressures of the bubbles between 13 and between the upstream side internal stabilizer 12 and the molding die are reduced almost so that the diameter of the bubbles B is reduced, and as a result, the internal bubbles of the upper and lower bubbles B are reduced.
It does not adhere to 12, 13 and avoids thinning of the bubble B and does not cause its breakage.

(Second Embodiment) An apparatus A'shown in FIG. 5 is a typical embodiment of the invention according to the second aspect of the present invention, in which a film of about 20 .mu.m used for a synthetic resin shopping bag is molded at an intermediate level. It is a device for.

The difference from the first embodiment is the downstream bubble internal stabilizer 13
Other than that, the same symbols as those of the first embodiment have the same structure as that of the first embodiment and have the same operation.

The downstream bubble internal stabilizer 13 'of this embodiment is formed by stacking three cylindrical body parts 13a, 13b, 13c having different diameters,
The diameter is larger on the downstream side. That is, of the three cylindrical body portions 13a, 13b, 13c, the cylindrical body portion 13a on the downstream end side has the maximum outer diameter, and the cylindrical body portion 13c on the upstream side end has the minimum outer diameter, The outer diameter of the cylindrical body portion 13b is an intermediate value between the maximum outer diameter and the minimum outer diameter. Further, the heights of the three cylindrical body portions 13a, 13b, 13c are the same in the illustrated example.

(Operation of Second Embodiment) Since the operation of this embodiment is not much different from that of the first embodiment except the operation of the downstream bubble internal stabilizer 13 ', the operation of the downstream bubble internal stabilizer 13' here. Only the description will be made and the others will be omitted.

When the forming speed of the film F is slow, the bubble B in a softened state is formed on the outer peripheral surface of the cylindrical portion 13a on the downstream end side having the maximum outer diameter.
Contact each other and neck in at this position, and the bubble B is expansively molded in the radial direction at a stretch. On the contrary, when the forming speed of the film F increases, the bubble internal stabilizer 13 'on the downstream side of the bubble B
The contact position to the outer periphery is sequentially moved to the intermediate cylindrical body portion 13b and the upstream end side cylindrical body portion 13c having the minimum outer diameter, and the position corresponding to the molding speed of the film F, that is, from the molding die 11. At the optimum height, the bubble B comes into contact with the downstream bubble internal stabilizer 13 ', and is stretched in the radial direction with the contact position as the neck-in position.

C. Effect of the Invention In the inflation film forming apparatus of the present invention configured and operating as described above, the annular cooling air outlet of the bubble cooling ring is opened at a position where the cooling air is blown toward the peripheral surface of the tapered bubble guide portion. The upstream maximum diameter of the tapered bubble guide portion matches the diameter of the cylindrical body portion, and the diameter of the downstream end of the upstream bubble internal stabilizer is the tapered bubble guide portion. Since it is formed to be smaller than the minimum diameter of this product, this device can be used to make ultra-thin films (especially high-density polyethylene) (about 10 millon) and 20-micron films used for synthetic resin shopping bags. MD, TD
It can be manufactured as a film with balanced strength in both directions.

Further, since each of the bubble internal stabilizers is provided with the communication hole, the bubble in the molten state is blown into the bubble from the internal air blowing pipe to expand it to a predetermined diameter, and then the bubble is directed to the exhaust port provided in the molding die. A part of the circulating air flow that flows in flows into the annular space through these communication holes, slightly increases the pressure in this space and reduces the diameter of the bubble to reduce, and avoids the thinning of the bubble. The judgment can be prevented in advance.

Even if the internal air is not always blown from the outside, the upper and lower spaces of each bubble internal stabilizer are communicated with each other through the communication holes, so that the atmospheric pressures of the spaces above and below are almost equal. Maintains a pressure state, and the bubbles are not particularly reduced between the upper and lower bubble internal stabilizers, and even if the operation is continued for a long time, the desired MD and TD strength in both directions can be formed into a film. .

Furthermore, the downstream-side bubble internal stabilizer has an overall inverted truncated cone shape, and the outer diameter D ₀ of its upper end (downstream end) is smaller than the outer diameter d 1 of the upper end (downstream end) of the bubble guide portion, Since the diameter is smaller toward the lower end and the outer peripheral surface is inversely tapered, an extremely thin film F of approximately A micron can be used to form an ultra-thin film F of approximately A micron, depending on the type of film, various high-speed molding speeds (for example, Inflation molding can be performed at a minute A0 m to 120 m / min), and the bubble can be stably molded without contact with the downstream bubble internal stabilizer.

Further, the automatic adjustment device can automatically change and adjust the expansion start portion of the tube to a predetermined height position to automatically correct the film tube to a predetermined reference expansion shape and a uniform expansion rate. The frost line can be automatically adjusted to a certain height as quickly as possible, and a stable and good-quality annular film can be easily manufactured.

Further, when the tube is operated in accordance with the expansion start position of the tube for obtaining the positions of the upper and lower detection devices, the expansion start position is automatically adjusted between the upper and lower detection devices, and the adjustment work is saved.

As an effect peculiar to claim 2, the downstream bubble internal stabilizer is formed by stacking at least three cylindrical body parts having different diameters, and the downstream side has a larger diameter. That is, among the three cylindrical body parts, the cylindrical body portion on the downstream end side has the maximum outer diameter, the cylindrical body portion on the upstream end side has the minimum outer diameter, and the outer diameter of the intermediate cylindrical body portion. Since it is an intermediate value between the maximum outer diameter and the minimum outer diameter, 40 m / min
A thick film of about 20 microns used for a synthetic resin shopping bag at a medium speed of about 85 m is brought into contact with the bubble B at a height corresponding to the molding speed and the downstream bubble internal stabilizer to prevent vibration. Moreover, stable molding can be performed without anybody.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 relates to the present invention, FIG. 1 is a schematic front view showing a control part of a first embodiment, FIG. 2 is a plan view showing a relationship between a detection device part and a tube, FIG. 3 is a block diagram of the control unit, FIG. 4 is a schematic half sectional view of a bubble internal stabilizer portion of the first embodiment, and FIG. 5 is a schematic half sectional view of a bubble internal stabilizer portion of the second embodiment. FIG. Main symbols 2 and 3 in the figure ... Detection device, 1a ... Expansion start position, C ... Control part, 6 ... Progressive / regressive level changing device, 12 ... Upstream bubble internal stabilizer, 12b ... … Bubble guidance part, 24, 25 ……
Communication hole.

Claims (2)

[Scope of utility model registration request] 1. A bubble in a molten state extruded from an annular discharge port of a molding die is supported from the inside by at least two upper and lower bubble internal stabilizers attached to an internal air blowing pipe, and is provided in the vicinity of the annular discharge port. The bubble is cooled from the outer peripheral surface by the cool air blown from the bubble cooling ring, and the bubble is expanded to a desired diameter on the downstream side of the downstream bubble internal stabilizer to form an inflation film of a predetermined width, and the expansion start point of the bubble is Vertical movement is detected by at least two sets of upper and lower non-contact detection devices, and when the rise of the expansion start point is detected, the cooling air discharge amount of the air ring is increased, and when the lowering is detected, this cooling air is detected. In an inflation film molding machine that reduces the discharge rate and automatically adjusts the frost line according to the blow ratio, The most upstream bubble internal stabilizer is a bubble guide cylinder portion having a diameter approximately equal to the diameter of the annular discharge port, and a taper shape which is located downstream of this cylinder portion and whose downstream side has a smaller diameter than the upstream side. Of the truncated frustoconical bubble guide part, at a position where the cool air is blown toward the peripheral surface of the tapered bubble guide part in the upstream bubble internal stabilizer.
The annular cold air outlet of the bubble cooling ring is open, the upstream maximum diameter of the tapered bubble guide portion matches the diameter of the cylindrical body portion, and the downstream bubble internal stabilizer is a hollow body. In addition, the diameter of the downstream end is formed to be smaller than the minimum diameter of the tapered bubble guide portion in the upstream bubble internal stabilizer, and the outer diameter of the downstream bubble internal stabilizer gradually increases toward the downstream side. Moreover, the hollow portion of the downstream bubble internal stabilizer is communicated with the outside through the communication holes provided in the upper and lower end plates, respectively.
The upstream bubble internal stabilizer is provided with a communication hole that penetrates vertically, and further, a machine frame near the expansion start point of the synthetic resin tube of the apparatus for manufacturing a film by the inflation method or a member integrated therewith. In addition, two sets of non-contact detection devices are provided above and below to detect the presence or absence of the film at the expansion start portion,
Depending on the presence or absence of these detection signals, the increase or decrease of the cooling air discharge amount from the air ring surrounding the tube is provided in the speed change of the blower rotation variable speed motor of the air ring or a part of the air system of the air ring. If the state of the output signal of the up-and-down detection device does not change from the previous detection state after the decrease or increase of the air discharge amount is continued for a predetermined time, the control unit is provided by adjusting the opening degree of the damper. The inflation film forming apparatus is further provided with an automatic adjusting device configured to further reduce or increase the air discharge amount and adjust the frost line to stabilize the height to a constant height. 2. The inflation film according to claim 1, wherein the downstream bubble internal stabilizer is formed by stacking at least three cylindrical portions having different diameters, and has a larger diameter toward the downstream side. Molding equipment.