JPH0342999Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Technical field to which this invention is applied] This invention is a device that is used to stabilize bubbles in a molten state when manufacturing a film using an inflation film forming machine. [Prior art and its problems] Conventionally, there are two types of bubble stabilizers of this type: a bubble stabilizer that supports bubbles from the inside, and a bubble stabilizer that supports bubbles from the outside. In the former model, when the film to be formed is thick, the blowing ratio is large, or the bubble take-up speed is slow, the bubble tends to start expanding from near the bubble stabilizer installed inside the bubble, and this It separates from the stable body and becomes unstable. In order to eliminate this unstable state, it is possible to bring this stabilizer close to the molding die from the beginning of operation, but the bubbles in the melted and soft state immediately after being discharged from the annular discharge port of the die will stick to the peripheral surface of the stabilizer. When you come into contact with
The bubbles break, making it impossible to remove the bubbles, making it impossible to perform the thick film and high-speed molding with a high blowing ratio, resulting in low productivity in the former case. One example is Japanese Patent Application Laid-Open No. 59-89122. As the latter model in which the expanded bubble is supported from the outside by a porous cylindrical body without using the inner stabilizer, the present applicant has proposed the "inflation film molding method" described in previously filed Japanese Patent Application No. 77322/1983. Developed a "bubble stabilizer" that prevents bubbles in the unstable part of the expansion process from being affected by the outside air, and prevents molding irregularities such as uneven wall thickness and stiffness in bubbles after expansion molding. , we were able to achieve the desired effect by keeping the film fold width constant and allowing high-speed take-off, but when forming a film whose surface has poor slipperiness after curing, contact between the porous cylindrical body and the outer peripheral surface of the bubble was difficult. As a result, this bubble becomes easily damaged,
There is still room for improvement in this respect. [Means for solving the problem] This invention improves the above-mentioned Japanese Patent Application No. 60-77322,
Inflation film molding with an air cooling device that cools the outer peripheral surface of the bubble discharged from the annular outlet of the molding die of the inflation film molding machine and expanded with inner air to form a tube with a desired fold width diameter. In the machine, a bubble stabilizing support device consisting of a porous cylindrical body that surrounds the expansion-molded bubble from the discharge port to the downstream of the bubble frost line is arranged in the housing part of the air cooling device. A cooling air supply chamber of the spot cooler device is formed on the outer periphery of the upper part of the bubble stabilizing support device with which the outer periphery of the bubble that is about to come into contact is formed with a part of the outer periphery of the porous cylindrical body as an inner wall. This stable bubble cooling device is used in a blown film forming machine that prevents the above-mentioned damage, supports the bubble more stably, and solves the above-mentioned problems. [Effects of this invention] In this invention, the cooling air supply chamber of the spot cooler device is formed on the outer periphery of the upper part of the porous cylindrical body, using a part of the porous cylindrical body as an inner wall.
The cooling air from the spot cooler passes through the small holes in the porous cylinder that forms the inner wall of this supply chamber, and is blown under static or dynamic pressure around the part of the bubble that has been expanded and molded within the porous cylinder. Between the inner surface of the body and the outer circumferential surface of this expansion-molded bubble part,
An air layer is formed around the entire circumference that takes the bubbles in, and the presence of this air layer prevents direct contact between the porous cylindrical body and the expanded portion of the bubble, and the bubbles are transported to the porous cylindrical body through the air layer. In addition to being able to stably support the bubble, the cooling effect on the bubble surface can be enhanced by the cooling air, and the porous cylindrical body does not scratch the bubble, allowing stable and high-speed molding regardless of the slipperiness of the resin. It is possible to produce tube strips with a constant folding width and less wrinkles and sagging. [Embodiments of this invention] Next, typical embodiments of this invention will be described based on the drawings. In FIG. 1, 10 is a molding die of an inflation film molding machine, and this die 10
The bubble 1 immediately after being extruded from the annular discharge port 11 of
An air cooling device 15 having an annular air outlet 14 surrounding the air cooling device 3 is fixed to the machine frame. A bubble stabilizing support device A is constituted by a porous cylindrical body 17 whose lower end is placed on the upper surface of the housing portion 16 of the air cooling device 15 and fixed with a fixture 17a. The inner diameter of this porous cylindrical body 17 corresponds to the outer diameter of the expanded portion 13a of the bubble 13, and its upper end reaches further downstream than the frost line L of the bubble 13. That is, the porous cylindrical body 17 is formed in a shape and size that surrounds the expansion-molded bubble 13 from the discharge port 11 to the downstream of the frost line L. At the upper end of this porous cylindrical body 17, an iris ring 18 whose bubble diameter can be adjusted is installed. On the upper outer periphery of the porous cylindrical body 17 with which the outer periphery of the expanded bubble portion 13a is about to come into contact, a cooling air supply chamber 20 of the spot cooler device 19 whose inner wall is a part of the outer periphery of the porous cylindrical body 17 is placed in a pinch state. A pair of bubbles are provided at positions corresponding to the center of the width of the bubble 13 when held between the rollers 22 (see FIG. 2). That is, the inner wall of the cooling air supply chamber 20 is a porous wall having small through holes 21 formed in the circumferential surface of the porous cylindrical body 17. The cooling air supply chamber 20 has a width in the axial direction of the bubble 13, and has a large number of cylindrical bodies 17 at once.
The shape is such that cooling air can be blown into the cylindrical body 17 through the small through hole 21 of the cylinder. Even if the cooling air supply port 20 is formed in an annular shape over the entire circumference of the porous cylindrical body 17, the invention remains the same. In the bubble stable cooling device of the present invention configured as described above, the bubbles 13 pushed out from the annular outlet 11 are connected to the annular outlet 1 of the air cooling device 15.
Due to the ventilate effect of the airflow blown out from the 4 parts, the bubble 13 starts to expand and
is cooled by the airflow flowing along its surface, and the outer circumferential surface of the expanded bubble 13 moves along the inner circumferential surface of the porous cylinder 17 as if in contact with it, and is taken downstream. At the upper part of this porous cylindrical body 17, cold air blown from the cooling air supply chamber 21 of the spot cooler device 19 is blown toward the outer peripheral surface of the bubble portion 13a expanded within the porous cylindrical body 17 through the small through hole 21. While cooling the outer peripheral surface, it merges with air from the upstream side and moves to the downstream side, forming a bubble portion 13a.
An air layer is formed between the porous cylindrical body 17 and the bubble 1
Direct contact between the bubble 13 and the porous cylindrical body 17 is avoided, the bubble 13 is stably supported, and a tube T having a constant fold width without scratches, wrinkles, or sagging can be formed at high speed. Furthermore, on the upstream side, most of the air heated by heat exchange with the bubble 13 is transferred to the porous cylindrical body 1.
Among the groups of small through holes 21 of No. 7, the groups of small through holes 21 from the outlet 11 that are not in contact with the bubble 13 at all during expansion of the bubble 13 are discharged out of the porous cylindrical body 17. Expansion molding can be carried out smoothly to a size that approximately matches the inner diameter of the porous cylindrical body 17 without being affected by outside air. As an effect of the embodiment, in the case where a pair of cooling air supply ports 20 are provided as shown in FIG.
The central part of the tube T can be cooled to the same temperature as both side edges in a shorter time, and the folded width diameter of the manufactured tube T can be made more uniform. Furthermore, in the case where the iris ring 18 is provided above the porous cylindrical body 17, the pressure between the bubble 13 and the porous cylindrical body 17 can be adjusted, and the bubble 13 can be supported more stably. In the embodiment in which the cooling air supply chamber 20 is provided over the entire circumference of the porous cylindrical body 17, the entire circumference of the bubble 13 can be cooled to the same temperature on average. Next, resin discharge rate 648Kg/h, extruder setting temperature

[Table] Furthermore, the temperatures around the tube at the measurement point B (points a to f shown in FIG. 2) were as follows.

[Table] The folding width diameter is also extremely stable, with an example of 655 mm.
It has become possible to form products with a folded width diameter of about 2 mm, with a difference between the maximum and minimum widths of about 2 mm.

[Brief explanation of drawings]

The figures relate to this invention; FIG. 1 is a schematic front view of a typical embodiment thereof, and FIG. 2 is a cross-sectional view taken along line 2--2 in FIG. 1. Explanation of the main symbols in the diagram, 13...Bubble, 17
... Porous cylindrical body, 19 ... Spot cooler device,
20...Cooling air supply room.

Claims (1)

[Claims for Utility Model Registration] 1. Air discharged from an annular outlet of a molding die of an inflation film molding machine, cooling the outer peripheral surface of a bubble expanded by inner air, and molding a tube with a desired folding width diameter. In an inflation film molding machine having a cooling device, the housing portion of the air cooling device includes a bubble stabilizing support device consisting of a porous cylindrical body that surrounds the expansion-molded bubble from the discharge port to the downstream of the bubble frost line. A cooling air supply chamber of a spot cooler device whose inner wall is a part of the outer circumferential surface of this porous cylinder is formed on the outer periphery of the upper part of the bubble stabilizing support device, which is arranged so that the expanded bubble outer circumferential surface is about to come into contact with the bubble stabilizing support device. A bubble stabilizing cooling device for use in an inflation film forming machine, characterized in that: 2. A pair of cooling air supply chambers of the spot cooler device are provided at positions corresponding to the center of the bubble width when pinched by the pinch rollers. Bubble stable cooling device. 3. The bubble stable cooling device for use in a blown film forming machine according to claim 1, wherein the cooling air supply chamber of the spot cooler device is open over the entire circumference of the porous cylindrical body.