JPS59103728A - Forming device of plastic pipe - Google Patents

Abstract

PURPOSE:To perform the smooth drive of a plastic pipe by providing sealant used when lapped edges are bonded to make a pipe body, a delivery mechanism for moving said pipe body toward the end of a mandrel, and the like. CONSTITUTION:Since a refrigerant passage 20 is provided by a step 21 between the end part 22 of the mandrel and a plastic pipe 6, and a cooling water outlet 24 is opened, cooling water is charged and runs in the refrigerant passage 20 as shown by the arrow and flows from the side of the plastic pipe end. Accordingly, even if molten film of high temperature from a T-type die 7 covers the external surface of the plastic pipe, the innermost layer part of the plastic pipe is cooled and not softened and the forward drive of the plastic pipe can be kept by the delivery mechanism 5. The molten film also is cooled uniformly and free from cooling distortion.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for forming a plastic tube used as a body member of a plastic can for storing food, drink, medicine, etc., for example.

BACKGROUND ART Plastic cans are desired to be mass-produced as containers for food, drink, or pharmaceuticals because they are easier to mass produce, process, and handle than metal cans or paper cans. To manufacture such plastic cans, a long plastic tube is formed by polymerizing and bonding the side edges of an original plastic film and winding it in a spiral shape, then cutting it into appropriate dimensions and using it as the body member. However, plastic tubes for body parts are required to have various physical properties depending on the purpose and the nature of the contents. A laminated plastic film base is used. For example, cans for food and beverages need to have water resistance, oil resistance, gas barrier properties, self-supporting properties, food hygiene properties, and cosmetic properties. For this reason, as shown in FIG. 1, for example, as shown in FIG. 1, the raw plastic film used for cans for food and beverages has a polyolefin layer such as a polyethylene layer, a polypropylene layer, or a polypropylene copolymer layer arranged on the lower layer A, and a middle layer B. A protective aluminum layer is placed on the surface to provide gas barrier properties.
When the above-mentioned polyolefin layer is arranged on the upper layer C and is used as a body member of a plastic can, the original fabric is stacked with the side edges of the original fabric in a spiral shape as shown in Figure 2. It is wound to form a cylindrical body E, and in order to eliminate the step between the overlapped side edge and D, a step is created between the overlapped side edge and D as shown in Fig. 3. A polyolefin layer F with a thickness corresponding to Cut into appropriate dimensions and make one piece. However, in this molding process, a high-temperature molten film is applied to a raw plastic film having low heat resistance, so the raw plastic film forming the inner tube becomes soft.

Teshima V4 has the disadvantage that the plastic tube tends to catch on the mandrel around which it is wound and becomes the core of the plastic tube, making it impossible to propel the plastic tube. The surface of the mandrel is wrapped with paraffin-coated waste paper, coated with Teflon or fluororesin, or treated with ceramics to improve the slippage of the mandrel, but even so, there is still a gap between the mandrel and the plastic tube. Frictional resistance occurs, making it impossible to propel the plastic tube, which, in addition to the above-mentioned problems, has been a drawback when forming plastic tubes.

It is an object of the present invention to provide a molding device that eliminates such drawbacks in molding plastic tubes, enables cooling of plastic tubes, and eliminates frictional resistance.

The present invention provides a mandrel whose outer circumferential surface is coated by overlapping the edges of original plastic film, a sealing member which forms a cylinder by bonding the overlapping edges, and a sealing member that forms a cylinder by bonding the overlapping edges, and a sealing member that connects the cylinder to the tip of the mandrel. The above object is achieved by having a delivery mechanism for sending the molten film toward the cylinder, and a die for applying a molten film to the outer surface of the cylinder, and by forming a refrigerant passage between the mandrel and the cylinder. It is.

Hereinafter, one embodiment of the present invention will be specifically described with reference to FIGS. 5 to 11.

In FIG. 5, which shows the overall arrangement of the plastic tube forming apparatus, a mandrel 2 around which a long plastic film material is spirally wound is fixed at its base end to a fixing member 3, and is held approximately horizontally. It is supported and installed in the center of the device. The proximal end of the cloak insole 2 is fixed by being clamped between two upper and lower crimp plates 3a, 3a, as shown in FIG. This is possible by rotating the knob 3b. Each member is arranged around the mandrel 2 supported and fixed in this way. 10 polymerized parts 1 of raw plastic film wound spirally around mandrel 2 without twisting
A sealing member 4 to which a is bonded is suspended from the mandrel 2''. As shown in FIG. 6, this sealing part 4 is arranged at a position where the plastic film raw fabric 1 overlaps the edge of the first raw fabric wound on the mandrel 2.
A red-hot coil 4b is provided inside the cylinder 4a, and this cylinder 4
Blowing hot air from a hose 4C connected to a onto the overlapping portion 1a of the plastic film raw fabric 1,
The overlapping portion 1a is welded and bonded to form a cylinder. A delivery mechanism 5 is installed at the longitudinally intermediate portion of the mandrel 2 to rotate the plastic tube formed into a cylinder by bonding the overlapping portion 1a and send it to the tip side of the mandrel 2. . As shown in FIG. 7, this delivery mechanism 5 includes rotary rolls 5a, 5a arranged to sandwich the mandrel 2 from the left and right sides, and the rotary rolls 5a, 5.
a and a plastic tube 6 wound around a mandrel, and a belt 5b wound in a figure 8 shape, and pedestals 5d and 5d connected by a screw rod 5C below each rotating roll 5a and 5a. By rotating the rotary roll 5 a +5 a by a motor (not shown),
While rotating the plastic tube 6,
slides on the fixed mandrel 2 and is fed out to the tip side of the mandrel 2, and at the same time pulls out the raw material 1 from the raw material roll 11 shown in FIG. 5 and applies tensile force to the plastic film raw material. It is the driving source that sends out the material while moving. The propulsion force and winding force of the plastic tube 6 can be adjusted by changing the distance between the pedestals 5d and 5d. The raw glass film 1 is gradually drawn out from the raw roll 11 by the action of the feeding mechanism 5, and first comes into contact with the coating roll 8 to have paraffin adhered to one side thereof. The purpose of this paraffin coating is to reduce the frictional resistance between the inner surface of the plastic tube 6 and the mandrel 2, thereby facilitating smooth propulsion of the plastic tube. The raw plastic film 1 is then reversed by a reversing roll 9, and one edge of the raw film is folded downward by an edge folding device 10. As shown in FIG. 5, this edge folding device 10 may adjust the tensile force of the original fabric while it passes between a plurality of rolls lOa, 10a, etc. to fold back the negative side edge portion downward. Also, as shown in FIG. 6, the interval between the regulating plates 10b, 10b is made smaller than the width of the original fabric, so that when the original fabric collides with the left regulating plate 10b, the - side edge thereof is lowered. It may be configured so that it is wrapped around. Alternatively, the rod may be brought into contact with one side edge of the original fabric and then folded back. The raw fabrics, which have been folded and overlapped at one side edge in the edge folding device 10 in this way, pass under the mandrel 2 and then are reversed so that the folded part is located upward. Then, it reaches the nip roll 16, and the above-mentioned adhesive sheet D is joined to the other side of the original fabric other than the folded overlapping part. This attachment sheet D is supplied from a sheet supply mechanism 15 provided on the left side of the mandrel 2. As shown in FIG. 10, this sheet supply mechanism 15 includes an adhesive sheet roll 15a, an application roll 15b for applying adhesive to the lower surface of this adhesive sheet roll 15, and a dryer 15c for drying this adhesive. Consisting of Therefore, the adhesive cartridge D pulled out from the wound adhesive sheet roll 15a is first coated with adhesive on the lower surface by the application roll 15b from the adhesive bucket 15d in which adhesive is stored, and then dried. In this state, the lower surface of the original fabric 1 is joined and bonded. When adhering this adhesive sheet, a nip roll 16 is provided. It is provided between the sheet supply mechanism 15 and the mandrel 2 for further adhesion. If the adhesive sheet is placed in the middle of the mandrel 2 in the longitudinal direction so that the adhesive sheet is crimped after the original fabric is spirally wound around the mandrel 2, the adhesive sheet cannot be positioned accurately, and the device may It becomes complicated and impractical. Such a nip roll 16 has a pair of upper and lower roll bodies 16a, 1 whose spacing can be adjusted as appropriate.
6a' is the main part thereof, but as shown in FIG. 11, a regulating ring 16C116c inserted through the rod 16b may be provided on the back side of the nip roll. The regulating rings 16c, 16c are capable of sliding on the rod 16b and are fixed in proper positions by screws 16d, 16d. Therefore, by setting the spacing between the regulating rings 16c and 16c to be approximately equal to the width of the pinning zone 3, it is possible to accurately position the pinning/-t D sent out from the note supply mechanism 15, so that the It becomes possible to accurately join one half of the The nip roll 16 is used to press the plastic material 1 and the adhering sheet (D) joined together in this way using roll pressure, and in order to strengthen this pressing force, the roll body 16a is used.

Either or both surfaces of 16a' may be coated with a rubber material or the like. In FIG. 11, a seal tube 17 provided close to the nip roll 16 is provided for blowing hot air onto the overlapping portion 1a of the folded original fabric to weld this portion. The structure is similar to that of the seal member 7 described above.

The plastic tube thus formed has the shape shown in FIG. 3 (9). Next, a molten film G is applied to the outer surface of the tube to give it cosmetic properties and rigidity, and the shape is changed to the shape shown in FIG. 4. Become. This molten film is extruded from a T-shaped die 7 provided above the mandrel on the tip side of the mandrel, as shown in FIGS. 9 and 5, and is applied to the plastic tube. To cool this molten film, a coolant passage 20 is formed between the mandrel 2 and the plastic tube body. This refrigerant passage 20 is filled with a refrigerant such as cooling water between the outer circumferential surface of the mandrel 2 and the inner circumferential surface of the plastic tube 6, so that the molten film G is not coated on the outer circumferential surface of the plastic tube 6. This is provided to cool the plastic tube in advance. In order to form this refrigerant passage 20, as shown in FIG.
A cooling water outlet 24 is formed to have a smaller diameter than that of the cooling water outlet 24 and open to the tip side portion 22 having a smaller diameter. This stepped portion 21 only needs to have a step that allows cooling water to flow into the refrigerant passage 20 formed between the small diameter portion 22 on the tip side and the plastic tube wound around the mandrel. .5 to 1 dragon is sufficient. Further, the length of the tip side portion 22 having a small diameter can be appropriately selected depending on the weight, diameter, etc. of the plastic tube. For example, if the inner diameter of the plastic tube is about 50 mm, it may be 150 to 200 mm. The step portion 21 is also formed to be located on the tip side of the seal member 4. If the seal member 4 is also formed on the proximal end side of the mandrel, the injected cooling water will leak from the unsealed overlapping portion, making it difficult to mold the plastic tube. Further, the cooling water outlet 24 communicates with a cooling water pipe 25 inserted longitudinally inside the mandrel from the proximal end side of the mandrel 2.
By connecting the base of 5 to, for example, a tap water faucet, tap water flows out from this outlet 24 and fills the refrigerant passage 20 between the small diameter portion 22 on the tip side of the mandrel 2 and the plastic pipe. to cool the inner layer of the plastic tube,
Even if the high temperature molten film extruded from the die adheres to the outer surface of the 70 plastic tube, the inner layer of the plastic tube will not become soft due to the effects of the heat.

FIG. 9 shows a state in which a plastic pipe is molded using the mandrel formed as described above.
The step 21 is formed 9, and a refrigerant passage 20 is formed between the tip end portion 22 of the mandrel and the plastic tube 6.
By opening the cooling water outlet 24, the cooling water flows while filling the refrigerant passage 20, as shown by the arrow, and flows out from the tip 1]l] of the plastic tube. Therefore, even if a high-temperature molten film from the T-shaped die 7 adheres to the outer surface of the plastic tube, the innermost layer of the plastic tube is cooled and does not become soft, so the delivery mechanism 5 maintains the propulsion of the plastic tube. be able to. In addition, the molten film that is applied is also cooled uniformly and solidified quickly, so there is no cooling distortion and a uniform coating film can be formed, making it possible to mold plastic pipes with excellent cosmetic properties. It is also possible to do so. Furthermore, since the cooling water is interposed between the tip end of the mandrel and the plastic tube, the contact area between the mandrel and the plastic tube is small, so there is less frictional resistance.
The propulsion of the pipe becomes even smoother.

FIG. 12 shows another embodiment of the mandrel. In this embodiment, the step portion 21 is formed with an inclined taper surface, and cooling water outlets 24 are also provided at two locations. Further, as shown in FIG. 13, the cooling water outlet may open from the proximal end portion 23 of the mandrel along the groove 26 to the small diameter portion 22 side. These differences are simply a matter of processing, and similar effects can be obtained in these cases as well. Similarly, for example, the cooling water outlet is 2
The mandrel 2 may be formed from a rod instead of a hollow tube.

In the above embodiments, the die may not be a T-shaped die, but a round die may be used for the application. Furthermore, although the side edges of the raw plastic film are shown folded back, the side edges may simply be overlapped without being folded back, and the plastic film may not be wound around the mandrel, but from the longitudinal direction of the mandrel. A cylindrical body may be formed by coating the outer peripheral surface of the mandrel so as to sandwich the mandrel and bonding the edges. or,
Since the overlapping parts are made of the same material, the sealing member and the sealing tube are shown to be welded by heating, but the overlapping parts may be adhered by applying an adhesive or the like to the original fabric. In these cases as well, effects similar to those of the above embodiments can be obtained.

As described above in detail, according to the present invention, when forming a 7° last pipe, the plastic pipe can be smoothly propelled, and the cosmetic effect of the surface can also be improved. becomes.

[Brief Description of the Drawings] Figure 1 is a perspective view of the original plastic film, Figure 2 is a perspective view of the plastic film in a spirally wound state, Figures 3 and 4 are cross-sectional views of the plastic tube, and Figure 4 is a perspective view of the original plastic film. Figure 5 shows the overall layout of the device.
Fig. 6 is a perspective view of a part thereof, Fig. 7 is a perspective view of the delivery mechanism, Fig. 8 is a cross-sectional view of the mandrel, Fig. 9 is a partially cutaway side view showing the state of molding, and Fig. 10 is a perspective view of the delivery mechanism. A side view of the sheet feeding mechanism, FIG. 11 is a perspective view of a nick 0 roll, FIG. 12 is a sectional view of the main part of another embodiment of the mandrel, and FIG. 13 is a main part showing still another embodiment of the mandrel. FIG. DESCRIPTION OF SYMBOLS 1... Original plastic film, 1a... Polymerization part, 2... Mandrel, 20... Refrigerant passage, 21...
- Stepped part, 22... Tip side part, 23... Base end part, 24... Cooling water outlet, 25... Cooling water pipe, 26...
...Groove, 3...Fixing member, 4...Sealing member, 5.
...Delivery mechanism, 6...Plastic tube, 7...Dice, 8...Coating roll, 9, 11...Reversing roll, 1o...Folding member, 16...Nip roll. Patent applicant Ajinomoto Co., Inc. Ace Package Co., Ltd. Agent Patent attorney 1) Masahiro Naka

Claims (1)

[Claims] A mandrel whose outer circumferential surface is coated by overlapping the edges of raw plastic film, a sealing member which adheres the overlapping edges to form a cylinder, and sends this cylinder toward the tip of the mandrel. A plastic tube forming apparatus comprising a delivery mechanism and a die for applying a molten film to the outer surface of the cylindrical body, and a refrigerant passage is formed between the mandrel and the cylindrical body.