JPH09300442A - Multilayered blow molding apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayered blow molding apparatus capable of conserving a raw material at the time of the replacement of a resin or a color and controlling the thickness of a multilayered parison. SOLUTION: A multilayered blow molding apparatus is equipped with a mandrel 19, a die upper part 1a having an inside sleeve 13 arranged so as to provide an inside annular passage 4 at the outside of the mandrel 19, and an outside sleeve 13 arranged so as to provide an outside annular passage 7 at the outside of the inside sleeve 13 and a die lower part 1b having a die 17 at its lower end part. The lower end of the inside sleeve 13 is positioned above the lower end of the outside sleeve 14 and the die lower part 1b is arranged in a slidable manner in the state being in contact with the outside surface of the outside sleeve 14 so as to regulate a gap 10 between the tip of the die 17 and a core pin 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-layer blow molding apparatus, and more specifically, it can save raw materials when changing resins or changing colors, and can reduce the thickness of a multi-layer hollow parison without generating weld lines. The present invention relates to a controllable multi-layer blow molding device.

[0002]

2. Description of the Related Art When molding a bottle or the like by using different kinds of resins in multiple layers, a resin in consideration of gas barrier property is used for a layer inside the container, and a resin outside the container is used. It has been attempted to achieve both gas barrier properties and surface glossiness by using a resin in consideration of surface glossiness in the layer. Thus, in the case of blow molding a multi-layered container utilizing the characteristics of the resin to be used, a hollow parison is formed in a multi-layered shape, and after sandwiching the multi-layered hollow parison with a mold, air is blown in, It is manufactured by taking out after cooling. As a device for forming a multi-layer hollow parison, the devices described in JP-A-55-107429 and JP-A-52-12273 are known.

The device described in JP-A-55-107429 is
It has a plurality of so-called side-feed type resin supply paths for supplying resin from a direction perpendicular to the extrusion direction of the hollow parison. The molten resin supplied from the supply passage collides with the mandrel for forming the hollow portion of the hollow parison, and then wraps around the mandrel along the annular flow path formed around the mandrel and is opposite to the supply passage. The resin flows combine on the side and flow downward. Then, the other resin flows that have flowed in the same manner join at the respective joining points, and the hollow parison formed in a multilayer shape is extruded from the tip of the die. The wall thickness of the hollow parison is controlled by moving the mandrel in the vertical direction and adjusting the gap between the core pin at the tip of the mandrel and the die.

However, in the above-mentioned apparatus disclosed in Japanese Patent Laid-Open No. 55-107429, since the molten resin is supplied from the side, the flow path design for evenly distributing the molten resin in the circumferential direction. However, there is a problem that unevenness in the layer thickness distribution in the circumferential direction occurs, and a defective molding portion called a weld line is likely to occur on the opposite side of the supply path. In addition, when changing or changing the type or color of the resin, it is necessary to push out the hollow parison with a new resin to remove the old resin from the inside of the die, but since the above-mentioned device is a side feed system, There is also a problem that the resin flow on the opposite side of the supply path is likely to be stagnant, and that a lot of time is required at the time of resin change and color change, and a large amount of wasted resin.

Further, in the apparatus described in JP-A-52-12273, the outermost layer is formed in the same direction on the same axis as the extrusion direction of the hollow parison, in addition to the side feed type resin supply passage as described above. It also has a so-called center feed type resin supply path for supplying the resin to be formed. Since the molten resin supplied by the center feed method is uniformly guided in an annular flow path in an umbrella shape and supplied downward, it is possible to generate a weld line on the container surface after molding by using both methods together. Instead, the resin and the color can be changed in a short time, and the wasted resin can be reduced. In addition, it is not realistic to use the center feed system for all the resin supply passages because of structural limitation, and only one of the plurality of resin supply passages can be the center feed system.

However, in the above-mentioned apparatus disclosed in Japanese Patent Laid-Open No. 52-12273, the resin feed path by the center feed system is arranged, and the mechanism for moving the core pin at the tip of the mandrel up and down cannot be arranged. Therefore, there is a problem in that the thickness of the hollow parison cannot be controlled by adjusting the gap amount between the core pin and the die. For this reason, there is a problem that it is not possible to change the wall thickness according to the shape of the bottle or the like to be formed, reduce the amount of resin used, and form an article such as a bottle or the like that is lightweight and has a short cooling time. Even if the shaft for moving the core pin up and down can be arranged, the shaft impedes the resin flow supplied by the center feed system, and the advantage of the center feed system cannot be obtained.

Therefore, an object of the present invention is to save the raw material at the time of changing the resin or the color and to control the thickness of the multi-layer hollow parison without generating weld lines. To provide a device.

[0008]

The invention according to claim 1 is a mandrel 1 for forming a hollow portion of a hollow parison.
9, the inner annular flow path 4 so as to surround the mandrel 19
A die upper portion 1a having an inner sleeve 13 arranged with an outer annular flow path 7 so as to surround the inner sleeve 13 and an outer sleeve 14 surrounding the inner sleeve 13.
And a lower die part 1b having a die 17 at the lower end for extruding the hollow parison, the lower end of the inner sleeve 13 is located above the lower end of the outer sleeve 14. The die lower portion 1b is formed separately from the die upper portion 1a, surrounds the lower portion of the mandrel 19 and is slidably arranged in contact with the outer surface of the outer sleeve 14. The above object is achieved by providing a multi-layer blow molding device characterized in that the gap 10 between the tip of the die 17 and the core pin 21 at the tip of the mandrel 19 is adjusted.

According to a second aspect of the present invention, in the first aspect of the invention, the circular cross-sectional diameter of the mandrel 19 at the side of the lower end portion of the outer sleeve 14 is smaller than the circular cross-sectional diameters above and below the mandrel 19. The multi-layer blow molding apparatus is characterized in that the mandrel 19 is formed in a drawn shape so that the size becomes smaller.

[0010] The invention described in claim 3 is the invention according to claim 1 or 2.
In the invention described in (3), the method of supplying the molten resin to the inner annular flow path 4 is a center feed method, and the method of supplying the molten resin to the outer annular flow path 5 is a side feed method. The present invention provides a multi-layer blow molding device.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a multi-layer blow molding apparatus of the present invention will be described below with reference to the drawings.
1 and 2 show a multi-layer blow molding apparatus according to the present embodiment. FIG. 1 is a sectional view of a die head for pushing out a parison according to the present embodiment, and FIG. 2 is an enlarged view showing a portion near a sliding portion between an outer sleeve and a die body. FIG.

The multi-layer blow molding apparatus of this embodiment is shown in FIG.
As shown in FIG. 3, a mandrel 19 for forming a hollow portion of a hollow parison, an inner sleeve 13 arranged so as to surround the mandrel 19 with an inner annular flow path 4 interposed therebetween.
And an upper die portion 1a having an outer sleeve 14 arranged so as to surround the inner sleeve 13 with an outer annular flow path 7 interposed therebetween, and a lower die portion 1b having a die 17 for extruding the hollow parison at the lower end portion. It has and.
These configurations are similar to those of the conventional device.

Thus, in the multilayer blow molding apparatus of this embodiment, the lower end of the inner sleeve 13 is the outer sleeve 1.
4, the die lower part 1b is formed separately from the die upper part 1a and surrounds the lower part of the mandrel 19 and the outer sleeve 1
4 is slidably arranged in contact with the outer side surface of the core 4, and the gap 10 between the tip of the die 17 and the core pin 21 at the tip of the mandrel 19 is adjusted.

Further, in the multilayer blow molding apparatus of this embodiment, the circular cross sectional diameter of the mandrel 19 on the side of the lower end portion of the outer sleeve 14 is smaller than the circular cross sectional diameters above and below the mandrel 19. The mandrel 19 is formed in a narrowed shape, and the molten resin supply system to the inner annular flow path 4 is a center feed system, and the molten resin supply system to the outer annular flow path 5 is a side system. It is a feed system.

The multi-layer blow molding apparatus of this embodiment will be described in more detail. The multi-layer blow molding apparatus of the present embodiment has a die head 1 as shown in FIG. 1 in order to form a hollow parison composed of two layers, an inner layer and an outer layer. The die head 1 is composed of the die upper portion 1a and the die lower portion 1b, and the die lower portion 1b is slidably arranged at the lower end of the die upper portion 1a.

The die upper portion 1a comprises a die body 11, the inner sleeve 13, the outer sleeve 14, the mandrel 19 and a ring-shaped engaging portion 12, and the mandrel 19 is provided below the die body 11. The ring-shaped locking portion 12, the inner sleeve 13, and the outer sleeve 14 which are coupled to the plurality of bolts 23 are arranged in order.
(Only one is shown in FIG. 1) and they are fastened together and integrated.

The die body 11 has a supply passage 2 for supplying the molten resin for the inner layer. The supply passage 2 is formed at the center of a hollow parison which is extruded after being horizontally formed from a barrel (not shown). It is bent along the axis A and communicates with the umbrella-shaped flow path 3.

The mandrel 19 has an upper end portion formed in a conical shape to form the umbrella-shaped flow path 3, a lower portion thereof is formed in a cylindrical shape, and a lower portion thereof is partially narrowed by a concave groove 20. The core pin 21 is formed below the core pin 21. The mandrel 19 and the ring-shaped engaging portion 12 are composed of a plurality of spiders 18, 18 ... Radially projected from the outer surface of the mandrel 19.
Are connected by The mandrel 19 is arranged so that its central axis coincides with the axis A.

The inner sleeve 13 has a substantially cylindrical shape, and a flange-shaped portion which locks the ring-shaped locking portion 12 and serves as a mounting portion to the die body 11 is formed on an upper portion thereof. ing. The inner diameter of the cylindrical portion of the inner sleeve 13 is larger than the outer diameter of the cylindrical portion of the mandrel 19, and the inner sleeve 13 forms the inner annular flow path 4 between the inner sleeve 13 and the mandrel 19. is there. A groove 6 is formed obliquely on the outer peripheral surface of the inner sleeve 13, and the groove 6 is in communication with a supply path 5 for supplying the molten resin for the outer layer at the uppermost portion thereof. The thickness of the cylindrical portion of the inner sleeve 13 is formed such that the portion below the groove 6 is thinner than the upper portion. Further, the lower end of the cylindrical portion of the inner sleeve 13 is formed so as to be narrow and thin.

The outer sleeve 14 has a substantially cylindrical shape, and a portion to be attached to the die body 11 is formed on the upper portion thereof. The inner diameter of the cylindrical portion of the outer sleeve 14 is made equal to the outer diameter of the portion of the inner sleeve 13 above the groove 5, and the outer sleeve 14 is placed below the groove 5 of the inner sleeve 13. The outer annular flow path 7 is formed between the portion and the portion. Further, the lower end of the cylindrical portion of the outer sleeve 14 is formed so as to be narrowed and thin similarly to the inner sleeve 13.

The inner annular flow path 4 and the outer annular flow path 7 merge at the lower end of the inner sleeve 13 to form a merged annular flow path 8. In addition, the mandrel 1 described above
The recessed groove 20 formed on the outer peripheral surface of the outer sleeve 9 is located on the side of the lower end of the outer sleeve 14. Therefore, the confluent annular flow channel 8 has a wider channel width than the inner annular flow channel 4 (or the outer annular flow channel 7) above it.

The lower part 1b of the die is the die body 1
5, the die holder 16 and the die 17, and the die holder 1 is provided below the die body 15.
6. The dies 17 are arranged in order, and they are integrally fastened together by a plurality of bolts 24 (only one is shown in FIG. 1). Further, a shaft 22 parallel to the axis A is attached to the die lower portion 1b, and the shaft 22 penetrates the die upper portion 1a and is coupled to a servo motor (not shown).

The die body 15 has a hole formed at the center thereof through which the lower part of the mandrel 19 is inserted, and the inner diameter of the center portion of the hole is made equal to the outer diameter of the lower end of the outer sleeve 14. The confluent annular flow path 8 is formed between it and the mandrel 19. The lower portion of the hole is narrowed, and accordingly, the flow passage width of the merged annular flow passage 8 is also narrowed downward. The die holder 16 is attached to the die body 15 so that the die 17 is sandwiched in a hole formed in the center thereof.

The die 17 has a substantially cylindrical shape, and a collar-shaped portion serving as a locking portion for the die holder 16 is formed on the upper portion thereof. The die 17 has a hole formed in the center thereof through which the core pin 21 at the lower end of the mandrel 19 is inserted, and the inner diameter of the hole is slightly continuous above the hole of the die body 15. It is squeezed and made constant at the center thereof to form the die land 9 between the core pin 21 and the bottom end thereof, and is slightly widened to form the gap 10 between the core pin 21 and the bottom end thereof. The die 17 is the die holder 1
6, the position of the core pin 21 can be finely adjusted by an adjusting screw (not shown).
It is adjusted so that the gap 10 between and is not biased.

Next, a procedure for forming a multi-layer hollow parison using the multi-layer blow molding apparatus of this embodiment will be briefly described.

The molten resin for the inner layer, which is melted in a barrel (not shown) and is supplied to the supply path 2 by a screw (not shown), is supplied to the umbrella-shaped flow path 3 through the supply path 2. In the umbrella-shaped channel 3, the molten resin for the inner layer is uniformly and evenly distributed, and passes through the plurality of spiders 18, 18 ...
Is supplied to.

Similarly, at the same time, the molten resin for the outer layer, which is melted in the barrel (not shown) and is supplied to the supply passage 5 by the screw (not shown), exits the supply passage 5 and the side surface of the mandrel 19 is reached. Then, they are passed through the groove 6 and meet on the opposite side of the supply path 5, and are supplied to the outer annular flow path 7 below.

The molten resin for the inner layer, which has passed through the inner annular flow path 4, and the molten resin for the outer layer, which has traveled through the outer annular flow path 7, merge at the lower end of the inner sleeve 13 and merge with each other. It is supplied to the annular flow path 8. The width of the confluent annular flow path 8 at this confluence portion is made large, and the combined multi-layered resin flow is thinned by the confluent annular flow path 8 which becomes thinner as it goes downward. ,
It is supplied to the die land 9.

In the die land 9, the shape of the hollow parison to be extruded is adjusted, and the resin flow passing through the die land 9 is extruded through the gap 10 as a multi-layer hollow parison. At this time, the thickness of the hollow parison is adjusted by moving the die lower portion 1b up and down by a servomotor via the shaft 22 to change the gap amount of the gap 10.

Although the tip of the inner sleeve 13 is located above the tip of the outer sleeve 14 in this embodiment, the tip of the inner sleeve 13 is located above the tip of the outer sleeve 14. If it is not located at the position, the portion of the outer surface of the hollow parison composed of the inner layer I and the outer layer O extruded from the gap 10 corresponding to the sliding movement of the die lower portion 1b is scratched as shown in FIG. May occur. This is because the molten resin is pulled when the die lower part 1b slides,
It is considered that this is because the flow at the boundary between the inner layer and the outer layer is disturbed by the tip of the inner sleeve 13 and the tip of the outer sleeve 14.

In the present embodiment, by arranging the tip of the inner sleeve 13 above the tip of the outer sleeve 14, the inner layer is already formed at the portion where the outer sleeve 14 and the die body 15 slide. The resin and the outer layer resin are joined together so that the flow of the joining point between the inner layer and the outer layer at the tip of the inner sleeve 13 is not affected by the sliding of the die body 15. Further, in the present embodiment, by further widening the channel width of the confluent annular channel 8 on the side of the sliding portion between the outer sleeve 14 and the die body 15, the thickness of the outer resin layer is increased. The flow at the boundary surface of the multi-layer flow at the tip of the outer sleeve 14 is not affected by the sliding of the die body 15.

Further, when the sliding speed of the die body 15 is high, the resin flow rate is large, and the viscosity of the outer layer resin is high,
Since the pulling force by the sliding of the die body 15 becomes large, the scratch X as shown in FIG. 4 is likely to occur on the outer surface of the hollow parison. Further, the thinner the outer resin layer is, the more easily it is affected by the slide of the die body 15, so that the scratch X is more likely to occur.

The multi-layer blow molding apparatus of the present embodiment is configured as described above, and according to the multi-layer blow molding apparatus of the present embodiment, it is possible to save raw materials at the time of resin change or color change, and to weld lines. Without causing
The thickness of the multi-layer hollow parison can be controlled.

The multi-layer blow molding apparatus of the present invention is not limited to the above embodiment. For example, in this embodiment, the mandrel 19 is formed with the concave groove 20 to form the confluent tubular flow path 8. The width of the flow channel was expanded further,
As shown in FIG. 3, the confluent tubular channel 8 ′ may be formed without forming the concave groove in the mandrel 19 ′. Further, in the multilayer blow molding apparatus of the present embodiment, two layers of hollow parisons were formed by the die head 1 described above, but the multilayer blow molding apparatus of the present invention forms a multilayer parison of three or more layers. In this case, the lower end of the outer sleeve (that is, the outermost sleeve) that slides with the lower part of the die may be positioned lower than the lower end of the inner sleeve (that is, the inner sleeve). An inner resin layer may be further joined inside the inner sleeve. Other points can be appropriately changed without departing from the spirit of the present invention.

[0035]

According to the first aspect of the present invention, in the die head for multi-layer blow molding, the molten resin joins upstream of the sliding portion between the outer sleeve 14 and the die body 15 and the die lower portion 1b. By sliding
It becomes possible to adjust the wall thickness of the parison, and it is possible to form an article such as a bottle that satisfies the physical properties such as compressive strength and ESCR and is thin and lightweight, has a short cooling time, and has a good appearance. Further, since it is difficult to generate scratches on the surface of the hollow parison, the sliding speed of the die body 15 can be increased, and the productivity can be improved in this respect as well.

According to the invention described in claim 2, according to claim 1
In addition to the above effects according to the invention described in (1), the mandrel 19 is squeezed so that the circular cross-sectional diameter of the mandrel 19 on the side of the lower end portion of the outer sleeve 14 is smaller than the circular cross-sectional diameters of the mandrel 19 above and below. The outer sleeve 14 and the die body 1 are formed into a shape, that is, by forming a groove 20 on the outer surface of the mandrel 19.
5, the flow passage width of the confluent tubular flow passage 8 on the side of the sliding portion with 5 is increased to increase the thickness of the resin flow (in particular, the outer layer resin flow), and further scratches are generated on the outer surface of the hollow parison formed. Can be difficult.

According to the invention described in claim 3, according to claim 1
Alternatively, in addition to the above-described effects according to the invention described in 2, the center-feed method and the side-feed method are used in combination to supply the molten resin, so that there is little stagnation of the resin and the resin change and color change can be performed in a short time In addition to being able to save raw materials, it is also possible to mold articles such as bottles having an excellent appearance and a uniform layer thickness distribution without generating weld lines on the resin surface (particularly the outer layer resin surface). .

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a multilayer blow molding device of the present invention.

FIG. 2 is an enlarged cross-sectional view showing the vicinity of the sliding portion between the outer sleeve and the die body in the embodiment of the multilayer blow molding apparatus of the present invention.

FIG. 3 is an enlarged cross-sectional view showing the vicinity of a sliding portion between an outer sleeve and a die body in another embodiment of the multilayer blow molding apparatus of the present invention.

FIG. 4 is an explanatory cross-sectional view showing a scratch generated on the outer surface of a hollow parison.

[Explanation of symbols]

 1 Die Head 1a Die Upper Part 1b Die Lower Part 2 (Inner Layer Resin) Supply Channel 3 Umbrella Flow Channel 4 Inner Tubular Flow Channel 5 (Outer Layer Resin) Supply Channel 6 Groove 7 Outer Tubular Flow Channel 8 Combined Tubular Flow Channel 9 Die Land 10 Gap 11 Die Body 12 Ring-shaped Locking Part 13 Inner Sleeve 14 Outer Sleeve 15 Die Body 16 Die Holder 17 Die 18 Spider 19 Mandrel 20 Recessed Groove 21 Core Pin 22 Shaft 23, 24 Bolt

Claims (3)

[Claims] 1. A mandrel 19 for forming a hollow part of a hollow parison, an inner sleeve 13 arranged with an inner annular flow path 4 interposed so as to surround the mandrel 19, and an inner sleeve 13 for surrounding the inner sleeve 13. A die upper portion 1a having an outer sleeve 14 arranged with an outer annular flow path 7 interposed therebetween, and a die 17 for extruding the hollow parison.
And a lower die portion 1b having a lower end portion, the lower end of the inner sleeve 13 is located above the lower end of the outer sleeve 14, and the lower die portion 1b is the die. It is formed separately from the upper portion 1a, surrounds the lower portion of the mandrel 19 and is slidably arranged in contact with the outer surface of the outer sleeve 14, and the tip of the die 17 and the mandrel 19 are disposed.
A multi-layer blow molding device characterized in that the gap 10 between the tip and the core pin 21 is adjusted. 2. The mandrel 19 is formed in a drawn shape so that the circular cross-sectional diameter of the mandrel 19 on the side of the lower end portion of the outer sleeve 14 is smaller than the circular cross-sectional diameters above and below the mandrel 19. Claim 1
The multi-layer blow molding device described in 1. 3. The method for supplying molten resin to the inner annular flow path 4 is a center feed method, and the method for supplying molten resin to the outer annular flow path 5 is a side feed method. The multi-layer blow molding device described in 1.