JPH0519892B2 - - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a plug device for forming a plastic cylindrical object, and is particularly suitable for forming a plastic cylindrical object, which is suitable for forming a foamed plastic cylindrical object. relating to a plug device for

(Prior Art) An apparatus for molding a cylindrical object using foamed plastic includes a first extruder 1 and a second extruder 2, as shown schematically in a side view in FIG. 5 and in a plan view in FIG. The plastic extruded from this extruder passes through a foaming die-plug device 3 and is made into a cylindrical shape, which is torn by a cutter into a sheet-like film, which is then wound from a take-up machine 4 to take-up machines 5 and 6. It's starting to get taken away.

In the conventional die-plug device 3, as shown in a schematic cross-section in FIG. An air ring 11 is arranged at a distance around the outer periphery of the part,
The structure is such that air is blown onto the plastic from the outer circumferential surface to cool it immediately after it comes out of the die body 9 in a cylindrical shape.

The plug 10 is made of a material with high thermal conductivity, such as aluminum, and has a structure that can be cooled from the inside, and the ratio of the lip diameter of the die 9 to the outer diameter of the plug 10 is an important factor in sheet forming. It has become one of the For example, in general molding of PSP (expanded polystyrene paper), the sheet width
For 1040 m/m, a combination of a die diameter of 180 to 22 m/mφ and a plug outer diameter of about 665 to 675 m/mφ is often used. The sheet that has passed through the plug 10 is then cut through a cutter 12 provided at the outlet of the plug 10.
It was cut open and taken away. Depending on the width of the sheet, one sheet is cut in one place to take out one sheet, two places are cut out to take out two sheets, and four places are cut out to take out four sheets.

(Problems to be Solved by the Invention) However, in the conventional plug device described above, the plastic cylindrical material discharged from the die 9 is cooled by the cooling air blown from the external air ring 11 immediately after discharge, and the outer surface of the plastic cylindrical material is is cooled, but
Since the inner surface of the plastic tube is not cooled, especially in the case of foamed plastic, the foamed cells on the surface become coarse and the surface condition deteriorates.

Further, even if the plug itself is cooled, foaming has been completed by the time the plastic tube passes through the plug 10, and therefore does not contribute to improving the sheet surface condition.

Therefore, it has conventionally been desired to cool the inner surface of the plastic cylindrical material immediately after it is discharged from the die 9, and as a means to deal with this, an internal water cooling jacket ring is installed at a position immediately after the discharge from the die 9. Attempts have also been made to cool and solidify the inner surface of the cylindrical object by bringing it into contact with a plastic cylindrical object, but the discharge angle of the cylindrical object changes depending on the relative position of the die 9 and the plug 10. Therefore, it is not only necessary to prepare several types of internal water cooling jackets with angles that match the molding conditions, but also in the case of foam sheets, the rapid foaming after discharge from the die creates corrugations in the circumferential direction of the cylindrical object. This creates folds and may not make good contact with the cooling jacket, which poses a practical problem.

Another method has been proposed in which an internal air ring is fixed to the tip of the die 9, an air introduction hole is provided in the core of the die body, and compressed air is blown through this hole. This method is impractical because of problems such as cooling the plastic material and breaking the plastic tube discharged from the die due to the high air pressure.

[Structure of the invention]

(Means for Solving the Problems) In order to solve the above-mentioned problems of the prior art, the present invention aims to extrude resin such as foamed plastic into a cylindrical shape through an annular slit of a die. In a plug device for expanding in the axial direction, a hollow shaft is inserted and supported so as to be slidable in the axial direction of the plug body, and cooling air is directed toward the inner surface of a plastic tube provided on the outer periphery of the tip of the hollow shaft. an internal air ring for blowing air, and a biasing means that causes the hollow shaft to protrude from the tip of the plug body, and the rear end of the hollow shaft is communicated with a cooling air supply system, and It is characterized in that the tip of the hollow shaft abuts the die regardless of the relative position between the inner air ring and the die, so that the internal air ring and the die are placed in a constant positional relationship.

(Example) The present invention will be described below with reference to the example shown in FIGS. 1 to 4.

FIG. 1 shows a longitudinal side view of an embodiment of a plug device 50 according to the present invention, in which reference numeral 1
3 indicates the plug body. The plastic tube P then slides while contacting the outer surface of the plug body 13 and is taken off in the direction of the arrow by a take-off roll (not shown).

At the axial center of the plug body 13, the plug body 13
A hollow core shaft 14 supporting the is inserted and fixed,
A flange 15 at the base end of this hollow core shaft 14 is attached to a flange 17 on the side of the movable frame 16 (second figure) with bolts 1.
8, 18... The movable frame 16 is placed on the rail 19 by an arrow A as shown in the second figure.
The plug device is mounted so as to be movable in the direction, so that the relative position of the entire plug device with respect to the die 9 can be changed.

Another hollow shaft 20 is slidably inserted into the hollow core shaft 14, and the plug body 1 of this hollow shaft 20
An internal air ring 22 having a ring-shaped nozzle 21 for ejecting air in a ring shape is provided at the tip protruding from the hollow shaft 20, and a compression spring is disposed between the base end of the hollow shaft 20 and the flange 17. 23 is interposed to bias the hollow shaft 20 in the protruding direction. Then, the protrusion 24 protruding from the inner circumferential surface of the hollow core shaft 14 is fitted into the small diameter portion 25 (or groove) formed on the circumferential surface of the hollow shaft 20, and the protrusion 24 hits the step portion 25A at the end thereof. The protrusion limit of the hollow shaft 20 is determined by the protrusion 24 coming into contact with the stepped portion 25A at the end thereof.

A heat insulating material 26 is installed around the hollow core shaft 14 that supports the plug body 13, and this heat insulating material 26 allows air to flow from the air inlet 27 provided through the base end flange 17 of the hollow shaft 20. Heat is removed from the introduced air and the exhaust air which passes through the inside of the plug body 13 from air holes 28, 28 opened at the front end of the plug body 13 and is exhausted through exhaust pipes 29, 29. In the figure, 30,
Reference numeral 30 denotes a throttle valve for adjusting the exhaust amount provided in the exhaust pipes 29, 29.

Next, the operation of the above embodiment will be explained.

FIG. 2 shows the plug device 50 in a standby state immediately after the start of operation, and the plug device 50 is placed at a position separated from the die 9 so as not to interfere with preparation for operation.

FIG. 3 shows a steady operating state, in which the plug device 50 approaches the die 9, is placed in a position suitable for molding, and is fixed by a fixture (not shown).
In FIG. 3, the relative distance L between the die 9 and the plug device 50 can be arbitrarily selected depending on the molding conditions.

During the steady operation, the internal air ring 22 is in contact with the die 9 and is always pressed against the die 9 side by the compression spring 23, so even if the relative distance L with the plug device 50 is changed, the die 9 and the internal air ring 22 does not change, and regardless of the position where the plug device 50 is placed, the inner surface of the plastic cylinder P immediately after being discharged from the die 9 is connected to the nozzle 21 of the internal air ring 22.
It is cooled by cooling air jetted from the

As shown in FIG. 4, the cooling air flows through an inlet pipe 31 which is led from a position where the plastic tube P that has passed through the plug device 50 is incised.
Cooling air is introduced into the central shaft 20 through the
The air that is ejected from the nozzle 21 of the internal air ring 22 and cools the plastic tube P is sent to the plug body 1 through the air holes 28, 28 on the front surface of the plug body 13.
3 and through the exhaust pipes 29, 29 to the throttle valve 3.
The exhaust amount is adjusted by 0.30 and released into the atmosphere.

〔Effect of the invention〕

As explained above, the present invention provides the following features:
An internal air ring is provided that blows air toward the inner surface of the plastic tube formed by the die, so even when foamed plastic is used, the inner surface of the plastic tube is cooled before reaching the plug. Therefore, the foamed cells do not become coarse and can be molded with a good surface condition.

Further, according to the present invention, the hollow shaft having an internal air ring is given the habit of protruding from the plug body by the biasing means, and the tip of the hollow shaft is brought into contact with the die regardless of the relative position thereof. Even if the relative positional relationship between the die and the plug device is changed, the relative positional relationship between the die and the internal air ring does not change, and therefore the position of the plug device can be changed arbitrarily even during operation.

Note that the present invention is not limited to the illustrated embodiments, and design changes may be made arbitrarily without departing from the technical idea of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional side view showing an embodiment of the present invention;
Fig. 2 shows the relationship between the device of the present invention and the die, and is a side view in a standby state, Fig. 3 is a sectional view showing the positional relationship between the plug device and the die during steady operation, and Fig. 4 shows the flow of cooling air. FIG. 5 is a side view showing a production line for forming sheets from plastic cylinders, FIG. 6 is a plan view thereof, and FIG. 7 is a schematic sectional view showing a conventional plug device. 9...Die, 13...Plug body, 14...Hollow core shaft, 16...Moving stand, 20...Hollow shaft, 2
2... Internal air ring, 23... Compression spring, 26
...insulating material, 27...air inlet, 28...air hole, 29...exhaust pipe, 30...throttle valve for adjusting exhaust volume, 50...plug device, P...plastic cylindrical object.

Claims (1)

[Scope of Claims] 1. In a plug device for diametrically expanding a plastic cylindrical object formed by extruding resin such as foamed plastic into a cylindrical shape from an annular slit in a die, the plug body slides in the axial direction. A hollow shaft is movably inserted and supported, an internal air ring is provided on the outer periphery of the tip of the hollow shaft for blowing cooling air toward the inner surface of the plastic tube, and the hollow shaft is inserted into the tip of the plug body. and a biasing means that causes the hollow shaft to protrude from the die, and communicates the rear end of the hollow shaft with the cooling air supply system, so that the tip of the hollow shaft contacts the die regardless of the relative position between the die and the plug device, and A plug device for forming a plastic cylindrical object, characterized in that an air ring and a die are placed in a fixed positional relationship. 2. The plastic according to claim 1, characterized in that the air supply system to the internal air ring is configured such that cooling air is supplied by inserting an introduction pipe from a cut-out part of the plastic cylindrical body. Plug device for forming cylindrical objects.