JPH09183152A - Preparation of hollow double wall molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely form a discharge hole for a pressurized fluid and to increase cooling speed by making the pressurized fluid flow without deviation in a hollow part of a hollow double wall molded article. SOLUTION: After a molten parison is arranged between opened molds 11 and 12, the molds are closed to form a pinch-off part 4 by placing the parison between mold compression parts 11b and 12b under a full flash condition. Then, a blowing means is plunged into the parison and a pressurized fluid is introduced therein to expand it along cavities 11a and 12a to form a hollow double wall molded article P1 and a nozzle 13 is plunged from the neighborhood of the pinch-off part through a nozzle inserting hole 14a of a guide push 14 to open a discharge hole by means of the nozzle 13 and the pressurized fluid is made to flow in the hollow part of the hollow double wall molded article P1 to cool it from the inside by discharging the pressurized fluid from the discharge hole.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow double-walled thermoplastic resin molding which has one wall and the other wall facing each other with a gap, and the peripheral edges of both walls are closed by end walls. The present invention relates to a method of manufacturing a product.

[0002]

2. Description of the Related Art Heretofore, various methods as described below have been known as methods for shortening a molding cycle time in blow molding a hollow molded article.

(A) As shown in FIG. 8, an air supply nozzle 104 and an exhaust gas which are moved forward and backward by an air cylinder 108 in a parison 103 sandwiched between one mold 101 and the other mold 102 that are closed. Nozzle 10
6 is pierced from a direction perpendicular to the axial direction of the parison 103, air is blown from the air supply nozzle 104 to expand along the cavity, and then the molded product is cooled in the mold, and the circulation embedded in each mold is performed. The cooling water is circulated in the water channel 109 to cool the molded product from the outside, and the air supplied from the air supply nozzle 104 is exhausted from the exhaust nozzle 106 so that the air flows inside the molded product and the inside of the molded product. Cooling method (Japanese Patent Laid-Open No. 60-8703)
No. 5).

(B) As shown in FIG. 9, a parison 203 sandwiched by one mold 201 and the other mold 202 that are closed is fitted in a hollow needle 205 so as to be movable in the axial direction. With the inserted empty needle 207 in a state in which the tip of the piston 207a in the cylinder 204 is projected by advancing the piston 207a, the parison is inserted through the suction hole 208 provided between the protrusion 206a of the sleeve 206 and the hollow needle 205. A vacuum is sucked on 203 to open a hole in the parison 203 with the empty needle 207, and then the empty needle 207 is retracted together with the piston 204a and pulled out from the hollow needle 205, and then air is supplied from the air supply port 209. A method in which air is blown into the parison 203 through the hollow needle 205 (see Japanese Patent Laid-Open No. 60-25725).

(C) As shown in FIG. 10, air is blown at once from a blow nozzle 304 into a parison sandwiched by one mold 301 and the other mold 302 that are closed, and at the same time, the mold is closed. Unnecessary portions of the tube container 303 in 301 and 302, that is, a communication opening 307 formed in a lower portion in the drawing from a planned cut portion 306.
The tube container 30 from the outlet 305 formed by
A method of quickly flowing the air in the tube container 303 by discharging the air in the No. 3 (Table 5-6119).
No. 06).

(D) As shown in FIG. 11, a delivery pipe 404 and a delivery pipe 404 are loosely fitted in a parison sandwiched between one die 401 and the other die 402 which are closed. Insert the small-diameter discharge pipe 405,
After introducing a higher temperature fluid to expand the parison while heating it to blow mold the molded product 403, the valve 4
06 to switch the low temperature fluid from the feed pipe 404 to the molded product 40.
A method in which the high temperature fluid is discharged through the discharge pipe 405 after being introduced into the inside of the chamber 3 and the low temperature fluid is caused to flow instead of the high temperature fluid and cooled (see Japanese Patent Publication No. 5-66852).

(E) Almost the same as the above (d) except that the room temperature fluid is introduced into the parison instead of the high temperature fluid in the above (d).
A method including the same steps as those described in JP-A-57-129724
Reference).

[0008]

However, the above-mentioned conventional techniques have the following problems, respectively.

In the above method (a), when the air supply nozzle and the exhaust nozzle are pierced into the parison, the parison may be deformed and escape into the cavity, so that the parison may not be reliably pierced. Since the tip end openings of the air nozzle and the exhaust nozzle are covered with the resin, and the amount of air flow is reduced, the cooling rate of the molded product is not so fast, and as a result, the shortening of the molding cycle cannot be achieved.

Although the method (b) can increase the diameter of the air injection hole of the parison, the structure of the air blowing means and the vacuum suction means of the parison is complicated, resulting in high cost and unevenness in the molded product. It is difficult to let air flow without it.

In the above method (c), the discharge port is formed by the pressure of air blown into it, or a hollow needle is pierced to use the hollow portion as the discharge port, or a solid needle is pierced and then pulled out. In any of the methods of forming the discharge port by the above, the resin deformed into a tubular shape or a plate shape may fall around the discharge port and block the discharge port.

In both the methods (d) and (e), the relative positions of the air supply portion and the air discharge portion in the parison are limited, and it is difficult to make the air flow evenly in the molded product. Therefore, even if the air supply amount is increased, the cooling rate of the molded product cannot be increased so much. It is also for blow molding a molded product having a large inner diameter mouth portion into which a double tubular nozzle can be inserted, such as a hollow container such as a bottle or a tank. When applied in the case of manufacturing a double-wall molded product having no, it becomes difficult to pierce the parison.

The present invention has been made in view of the above-mentioned unsolved problems of the prior art. The discharge port for the pressurized fluid can be reliably formed, and the hollow double wall molded article can be formed in the hollow portion. It is an object of the present invention to realize a method for manufacturing a hollow double-walled molded product that allows a pressurized fluid to flow evenly and to increase the cooling rate.

[0014]

In order to achieve the above object, the method for producing a hollow double-walled molded product according to the present invention has one wall and the other wall facing each other with a space therebetween. In a method for manufacturing a hollow double-wall molded product in which a peripheral edge portion is closed by an end wall, one mold having a cavity for regulating an outer surface of the one wall and a part of the outer surface of the end wall, and The mold of the split type provided with the other mold having a cavity for regulating the outer surface of the other wall and the outer surface of the remaining portion of the end wall is opened, and the mold of the split type opened. A pinch-off portion is formed by placing the molten parison in between and then closing the mold to sandwich the parison, after which a blowing means is inserted into the parison to introduce pressurized fluid and expand along the cavity. Let the hollow double wall molded product The hollow double-wall molding is performed by forming the discharge port by opening the discharge port by piercing the nozzle from the vicinity of the pinch-off part, and then introducing the pressurized fluid from the blowing means and discharging the pressurized fluid from the discharge port. It is characterized in that the pressurized fluid is made to flow evenly in the hollow portion of the article to be cooled.

Another method for manufacturing a hollow double-wall molded product is a hollow double-walled product having one wall and the other wall facing each other with a gap, and the peripheral edges of both walls being closed by an end wall. In the method for manufacturing a wall molded article, one mold having a cavity for regulating the outer surface of the one wall and the outer surface of a part of the end wall, and the outer surface of the other wall and the rest of the end wall. The mold of the split type provided with the other mold having the cavity for regulating the outer surface of the part is opened, and the molten parison is arranged between the molds of the split opened type and then the mold is closed. A pinch-off part is formed by sandwiching the parison, and then a blow-in means is inserted into the parison to introduce a pressurized fluid and expand along the cavity to form the hollow double-wall molded product. Together with the pinch-off section To form a plurality of openings for piercing the nozzle from the inside to allow the pressurized fluid in the hollow portion to flow, and to introduce the pressurized fluid from at least one of the openings and discharge the pressurized fluid from the remaining openings. Then, the pressurized fluid is uniformly flowed and cooled in the hollow portion of the hollow double-wall molded product.

[0016]

Since the discharge port is formed by piercing the nozzle from the vicinity of the pinch-off portion formed by the mold of the closed type in which the mold is closed, the discharge port can be surely opened and the part forming the discharge port is The outlet can be opened at a portion where the pressurized fluid can flow in the inside of the hollow double-wall molded article without being restricted by the portion that pierces the blowing means.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings.

(First Embodiment) First, an example of the hollow double-wall molded product manufactured according to the first embodiment will be described.

As shown in FIG. 1, a hollow double wall molded product P ₁
Is blow molded from a thermoplastic resin,
One wall 1 having a flat surface and the other wall 2 having a plurality of recessed ribs 2a face each other with a space therebetween, and peripheral edges of the both walls are closed by an end wall 3. Along with the pinch-off portion 4 formed at 1, the holes 5 are formed with a plurality of nozzles pierced at intervals.

Next, the steps of the method for producing the hollow double-wall molded product of this embodiment will be described.

As shown in FIG. 2 and FIG. 3, a cavity 11a surrounded by a mold compression portion 11b for restricting the outer surface of one wall 1 and a part of the end wall 3, that is, the outer surface of about half is formed. A plurality of nozzle fitting holes 14 that have a plurality of axially penetrating holes that are provided at intervals along the mold compression portions 11b on both sides of the cavity 11a in the drawing.
One mold 11 provided with a guide bush 14 having a
And correspondingly, the periphery for restricting the outer surface of the other wall 2 and the outer surface of the remaining part of the end wall 3 is the mold compression portion 12
A plurality of fitting recesses 1 each having a cavity 12a surrounded by b and in which each guide bush 14 is loosely fitted when the mold is closed.
The split type mold including the other mold 12 provided with 2c is opened.

After the above steps, as shown in FIG. 3, a molten parison 22 made of a thermoplastic resin is extruded from an extruding head 21 of an extruding machine (not shown) to open the molds 11 and 12 of the split type. Place it in Fig. 4
As shown in FIG. 5, the pinch-off portion 4 is formed by clamping the parison 22 with the die compression portions 11b and 12b in a total burr state by closing the die.

In this case, the pinch-off portion 4 is formed on the end wall 3, and the burr 2 is formed on the pinch-off portion 4 via the thin portion 23b.
3 is connected. Further, the burr 23 is formed with a curved portion 23a having a shape along the outer peripheral surface of the guide bush 14.

In this step, the front end opening of the parison 22 is closed before the mold is closed, and a predetermined amount of pressurized fluid such as pressurized air is introduced by the blowing means provided inside the extrusion head 21, that is, so-called. It is recommended to complete the mold closing after pre-blowing.

After the above steps, a blowing means such as a blowing needle (not shown) is thrust into the parison 22 and a pressurized fluid such as pressurized air is introduced and expanded along the cavity to form a hollow double-wall molded product P. ₁ is formed, and the nozzle 13 is pierced from the vicinity of the pinch-off portion 4 through the nozzle fitting insertion hole 14a of the guide bush 14 to open the discharge port by the nozzle 13 and to introduce the pressurized fluid from the blowing means. By discharging the pressurized fluid from the discharge port, the pressurized fluid flows evenly in the hollow portion of the hollow double-wall molded product P ₁ . As a result, in the molds 11 and 12, the hollow double-wall molded product P ₁ is rapidly cooled from the inside.

The blowing means including a blowing needle in this step forms a hole 6 in which the blowing needle is pierced in the other wall 2 when piercing the appropriate portion of the other wall 2 of the parison 22. As a result, a hollow double-wall molded product P ₁ having no holes in one wall 1 can be manufactured.

After the above steps, when cooling is completed, the mold is opened to take out the hollow double-wall molded product P ₁ and remove unnecessary burrs 23.

In the present invention, the guide bush 14 is
It is important that the parison 22 is arranged so as to intersect the portion where the pinch-off portion 4 is formed, that is, the mold compression portions 11b and 12b. Thus, when the nozzle 13 is stabbed, the pinch-off part 4 is held by the mold compression parts 11b and 12b, so that the discharge port can be opened by piercing the cavity without escaping inside.

(Second Embodiment) In this embodiment, as shown in FIG. 6, one wall 31 having a flat surface and a plurality of recessed ribs 3 are provided.
The other wall 32 having 2a faces the other wall with a space therebetween, and the peripheral edges of the both walls are closed by end walls 33, and the nozzle is pierced along the pinch-off portions 34 formed on the upper and lower end walls 33 in the figure. The hollow double-walled molded product P ₂ in which the holes 35 are formed is manufactured.

In this embodiment, as shown in FIG.
It has a cavity 41a that regulates the outer surface of one wall 31 and a part of the outer surface of the end wall 33, that is, the outer surface of about half of the end wall 33.
To regulate one die 41 having a guide bush 44 similar to the guide bush 14 of the first embodiment, and correspondingly the outer surface of the other wall 32 and the outer surface of the remaining part of the end wall 33. The other mold (not shown) having a cavity and a fitting recess in which each guide bush 44 is loosely fitted in the mold compression part is used, and the parison is extruded from the extrusion head 51 when the mold is closed. The pinch-off portion 34 is formed by sandwiching the upper and lower ends of 52 in the axial direction in the drawing. The other steps may be the same as the steps of the first embodiment described above, and thus the description thereof will be omitted.

The timing at which the nozzle 13 is pierced from the vicinity of the pinch-off portion 4 is as follows: completion of mold closing, introduction of a pressurized fluid by a blowing means such as a blowing needle, and introduction of a pressurized fluid into a hollow double-walled product P ₁ Any of the above may be used,
It is preferable that the parison is sealed and pierced in a state in which the internal pressure is maintained in the parison by pre-blowing or subsequent main blowing in order to prevent piercing failure.

Further, the part which pierces the nozzle 13 is the end wall part of the hollow double-wall molded product P ₁ having the pinch-off part,
In addition, it is preferable that the pinch-off portion 4 is bent and formed so as to surround the portion where the nozzle 13 is pierced by the pinch-off portion 4 as in the curved portion 23a in FIG.

Further, the cooling process by the flow of the pressurized fluid in the hollow portion of the hollow double-wall molded product P ₁ after molding is performed by introducing and discharging the pressurized fluid, and the nozzle 13 as in the first embodiment. When using 6 pieces, 3 places for introduction,
It can be used in 3 places for discharge. Further, in the cooling step, the part used for the introduction may be switched to the discharge, or the part for introducing the pressurized fluid by the blowing means may be used for the introduction or the discharge in the cooling step.

Regarding the discharging position, the flow nozzle or the blowing nozzle may be pierced, and then the hole may be opened after the flow nozzle or the blowing nozzle is removed.

In particular, when molding a hollow double-wall molded product, unlike the case of molding a general tank or bottle, the volume of the hollow portion is extremely small with respect to the internal surface area of the resin to be cooled, It is necessary to increase the supply amount of air or other known fluid, increase the hole diameter of the opening for introducing or discharging, or increase the diameter of the opening for flowing the pressurized fluid in the hollow portion formed by the nozzle 13. Location (eg 2-1
Providing a large number of (5 locations) is useful in molding a hollow double-wall molded product.

[0036]

Since the present invention is configured as described above, it has the following effects.

Since the discharge port is formed by piercing the nozzle from the vicinity of the pinch-off portion, the discharge port can be reliably formed by a simple device, and the discharge port is introduced from the introduction hole to the introduction hole for the pressurized fluid. It is possible to form the positional relationship such that the pressurized fluid flows in the hollow portion of the hollow double-wall molded product without unevenness and is discharged from the discharge port.
As a result, the cooling efficiency is improved and the molding cycle can be significantly shortened.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing an example of a hollow double-wall molded product manufactured according to the first embodiment of the present invention.

FIG. 2 is an explanatory view showing a relationship between a nozzle piercing portion and a mold in the hollow double-wall molded product according to the present invention.

FIG. 3 is an explanatory diagram showing a nozzle piercing portion in the first embodiment of the present invention.

FIG. 4 is a schematic partial cross-sectional view showing a state before piercing the nozzle in a portion along the line AA in FIG.

5 is a schematic partial cross-sectional view showing a state after the nozzle has been pierced in a portion along the line AA in FIG.

FIG. 6 is a schematic perspective view showing an example of a hollow double-wall molded product manufactured according to the second embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a nozzle piercing portion in the second embodiment of the present invention.

FIG. 8 is a schematic cross-sectional view of a mold main part in an example of a conventional method for manufacturing a hollow molded product.

FIG. 9 is a schematic cross-sectional view of a mold main part in another example of the conventional method for manufacturing a hollow molded product.

FIG. 10 is a schematic cross-sectional view of a mold main part in an example of a conventional tube container manufacturing method.

FIG. 11 is a schematic cross-sectional view of a mold main part in an example of a conventional method of manufacturing a container having a mouth part.

[Explanation of symbols]

 1,31 One wall 2,32 Other wall 2a, 32a Recessed rib 3,33 End wall 4,34 Pinch-off part 5,35 Hole piercing nozzle 6,36 Hole piercing blowing needle 11,31 One Mold 11a, 12a, 41a Cavity 11b, 12b, 41b Mold compression part 12 Other mold 13,43 Nozzle 14,44 Guide bush 21,51 Extrusion head 22,52 Paris 23 23 Burr 23a Curved part

Claims (2)

[Claims] 1. A method for producing a hollow double-walled molded product, comprising one wall and another wall facing each other with a space therebetween, and the peripheral edges of both walls being closed by an end wall. One mold having a cavity for restricting the outer surface and a part of the outer surface of the end wall, and the other mold having a cavity for restricting the outer surface of the other wall and the outer surface of the remaining part of the end wall. A pinch-off part is formed by opening a mold of a split type equipped with a mold, arranging a molten parison between the molds of the split type opened, and then closing the mold to sandwich the parison. ,
After that, a blow-in means is inserted into the parison to introduce a pressurized fluid and expand along the cavity to form the hollow double-wall molded article, and the nozzle is pierced from the vicinity of the pinch-off portion to form the discharge port. After the opening, the pressurized fluid is introduced from the blowing means and the pressurized fluid is discharged from the discharge port to allow the pressurized fluid to flow evenly in the hollow portion of the hollow double-wall molded article for cooling. A method for producing a hollow double-wall molded product, comprising: 2. A method for producing a hollow double-walled molded product, which has one wall and the other wall facing each other at a distance, and the peripheral edges of both walls are closed by an end wall. One mold having a cavity for restricting the outer surface and a part of the outer surface of the end wall, and the other mold having a cavity for restricting the outer surface of the other wall and the outer surface of the remaining part of the end wall. A pinch-off part is formed by opening a mold of a split type equipped with a mold, arranging a molten parison between the molds of the split type opened, and then closing the mold to sandwich the parison. ,
After that, the blowing means is inserted into the parison to introduce a pressurized fluid and expand along the cavity to form the hollow double-wall molded article, and the nozzle is pierced from the vicinity of the pinch-off portion to allow the inside of the hollow portion. Forming a plurality of openings for flowing the pressurized fluid, at least one of which
By introducing the pressurized fluid from the individual openings and simultaneously discharging the pressurized fluid from the remaining openings, the pressurized fluid is evenly flowed and cooled in the hollow portion of the hollow double-wall molded article. A method for producing a hollow double-walled molded product.