JPH0624754B2 - Multi-chamber blow molding apparatus and method - Google Patents

Description

Detailed Description of the Invention a. Object of the Invention (Industrial field of application) The present invention is to position a hollow cylindrical molten parison extruded from an extrusion die in the molding space of a mold and blow air into the space inside the parison to remove the above-mentioned molding space. The present invention relates to a blow molding device and a method for molding a hollow molded product corresponding to a shape.

(Prior Art) Such blow molding has been widely used since a resin molded product having a predetermined shape can be easily manufactured by setting the molding space to a predetermined shape.

In this case, taking advantage of the ease of setting the molding shape of blow molding, the inner surface of the parison is welded during blow molding, and a plastic fuel tank having a partition plate inside or a plurality of fuels is used. A method of molding a plastic fuel tank or the like having a chamber has also been proposed (Japanese Patent Laid-Open No. 62-140818 and Japanese Utility Model Laid-Open No. 63-11).
9024, etc.).

Further, a method for forming a hollow molded container having a double wall has been proposed by the present applicant (for example, JP-A-60-671).
30 and 60-71233, etc.). 2 like this
A container with a heavy wall has the advantage that even if there is a hole in the wall on one side, the wall on the other side can prevent the contents contained in the container from leaking out. There is an advantage that the heat insulation of the container is good due to the heat insulating effect of air.

(Problems to be Solved by the Invention) However, the container having the double wall must have a shape in which one end side is largely opened, and in order to use this as a closed container, a lid for covering the open side is provided. There is a need. Therefore, the above-mentioned molding method has a problem that a closed container such as a fuel tank cannot be manufactured.

The present invention has been made in view of the above problems, and an object thereof is to provide a blow molding apparatus and method capable of easily manufacturing a double-wall closed type container such as a fuel tank having a double wall. .

B. Configuration of the Invention (Means for Solving the Problems) In order to achieve the above-mentioned object, a molding apparatus according to the present invention comprises an extrusion die for parison extrusion and a molding of a predetermined shape for receiving a molten parison extruded from the parison extrusion die. Further, the extrusion die has an opening and a closing die each having a shape such that a cylindrical parison having a plurality of longitudinally extending closed cross-section chambers is extruded on the extruding end surface thereof. It has a plurality of air injection holes for supplying / discharging (supplying / discharging) blow molding air in the cross-section chamber.

Further, the molding method according to the present invention is a method of blow molding using the above-mentioned extrusion die and mold, and closes one end of the molten parison extruded from the opening in the parison extrusion die having the above structure. The molten parison is positioned in the molding space of the mold, and then air is supplied or discharged into each closed cross section of the molten parison from a plurality of air injection holes formed in the parison extrusion die to have a plurality of closed cross sections. At the same time, a hollow molded product having a predetermined shape that matches the shape of the molding space of the mold is molded.

(Operation) By performing such blow molding, it is possible to control the amount of air to be supplied to and discharged from each closed cross section of the molten parison to arbitrarily adjust the size of each closed cross section in the hollow molded product. Therefore, for example, a plurality of closed cross-section chambers are configured by a central closed cross-section chamber located at the center and a plurality of peripheral closed cross-section chambers surrounding the central closed cross-section chamber. The chamber is formed as a container inner space, and the amount of air supplied and discharged to each closed cross section is adjusted to form a space surrounding the central closed cross section chamber by the peripheral closed cross section chamber. It is also possible to hollow-mold a container having a surrounding double wall. According to this blow molding,
Not only can such a container having a double wall be molded, but various applied moldings such as the manufacture of a pipe having a predetermined bending shape divided into a plurality of passages can be performed.

(Examples) Hereinafter, preferred examples of the present invention will be described with reference to the drawings.

FIG. 1 shows a schematic structure of a blow molding device according to the present invention. This device comprises a parison extrusion die 10 for extruding a molten parison 1 and a pair of left and right molds for receiving the parison 1 below the die 10. 50 and 60. The parison extrusion die 10 is attached with parison pinches 9 and 9 for closing the extruded molten parison 1 with the lower end sandwiched therebetween.

The molds 50 and 60 are main bodies 51 and 61, respectively, having recesses 52 and 62 for forming a molding space of a predetermined shape.
And a pair of cylinder devices 55, 56 and 65, 66 for holding the main bodies 51, 61. Therefore, the rod 5 of the cylinder device 55, 56, 65, 66 is
By expanding / contracting 5a, 556a, 65a, 66a, the main bodies 51, 61 can be moved to the left and right so as to move closer to or away from each other. Neck portions 52a and 62a for forming an injection port of a tank formed by the molds 50 and 60 are formed at the upper ends of the recesses 52 and 62.

The structure of the parison extrusion die 10 will be described in detail with reference to FIG.

The die 10 includes cylindrical first, second, third and fourth outer members 18, 20, 25 and 2 which are vertically stacked.
7, first and second inner members 11 and 15 arranged in holes formed vertically through the outer members 18, 20, 25 and 27, and the outer and inner members. First and second intermediate members 30, 35 arranged between
Composed of and. First outer member 18 and second outer member 2
0 is connected by a plurality of bolts 42, and the second outer member 20 and the third outer member 25 are connected by a plurality of bolts 43, respectively, and the third outer member 25 and the fourth outer member 27 connect the pressing member 26. It is connected by a plurality of bolts 44 via.

The upper end of the second inner member 15 is screwed onto the lower end of the first inner member 11, and the two members 11 and 15 are joined in a state of vertically extending. The inner members 11 and 15 thus combined are
In this state, the outer member 18 coupled as described above,
While being placed through the central hole of 20, 25, 27,
The flange portion of the first inner member 11 is fixedly coupled to the first outer member 18 by bolts 41.

The first intermediate member 30 is a substantially disk-shaped member having an inner hole, and the second intermediate member 35 extends downward from a disk-shaped flange portion 35a formed on the upper portion and an inner diameter side portion of the flange portion 35a. It is a member composed of the cylindrical portion 35b. The flange portions 35a of the first intermediate member 30 and the second intermediate member 35 are sandwiched between the second and third outer members 20 and 25 so that both intermediate members 30 and 35 are fixed and held.

The first and second inner members 11 and 15 are formed with first air injection holes 12 and 16 which vertically penetrate through the central portions thereof, and the air injection holes 12 and 16 are provided at the upper part of the first air tube 45. , And the lower end is open.

The first outer member 18 is formed with a resin passage 19 having a first resin injection port 19a that opens to the outer surface. First
The inner hole surface 18a of the outer member 18 is in close contact with the outer peripheral surface 11a of the first inner member 11, and between the groove formed on the outer peripheral surface of the first inner member 11 and the inner hole surface 18a, a broken line in the drawing shows. A resin passage 13 having a good number is formed as shown in FIG. The resin passage 13 communicates with the resin passage 19 at its upper end and opens at a contact portion with the second outer member 20 at its lower end.

The second outer member 20 is formed with four vertically extending resin passages 22 having the shape shown in FIG. 3, which is a sectional view taken along the arrow III-III. The resin passage 22 communicates with the resin passage 13 at the upper end thereof, and has the first end at the lower end.
It opens at the contact surface with the intermediate member 30.

The second outer member 20 is further formed with a resin passage 21 having a second resin injection port 21a opening to the outer side surface, avoiding the resin passage 22 as shown in FIG. First
A spiral groove 14b is formed on the outer peripheral surface of the inner member 11 facing the inner hole surface 23 of the second outer member 20, and a spiral resin passage 14a is formed between the inner member 23 and the inner hole 23 surface. To be done. The upper end of the spiral resin passage 14a communicates with the resin passage 21. First inner member 11
The outer peripheral surface of the is closely contacted with the inner hole surface 23 at the upper part, but is gradually separated from the inner hole surface 23 at the lower part, and a cylindrical inner space 49 is formed between the outer peripheral surface and the inner hole surface 23. In addition, the outer peripheral surface of the second inner member 15 has a second
The inner space 49 is separated from the inner hole surface 39 of the intermediate member 35, extends to this portion, and opens at the lower end of the fourth outer member 27, that is, the lower end of the die 10.

At the upper end of the first intermediate member 30, four resin passages 32 communicating with the resin passage 22 are formed.
This resin passage 32 penetrates vertically, and the four resin passages 3 formed in the flange portion 35 a of the second intermediate member 35
8 (see FIG. 4 showing a cross section taken along arrow IV-IV). The resin passage 38 is formed so as to penetrate the flange portion 35a, and the lower end thereof has the second intermediate member 35.
The outer peripheral surface of the cylindrical portion 35b and the third and fourth outer members 2
5, 27 open to a cylindrical outer space 48 formed between the inner hole surfaces 25a, 27a. The outer space 48 opens at the lower end of the die 10.

The first intermediate member 30 has an L shape in which one end communicates with a second air tube 46 that is provided penetrating the third outer member 25 and the other end opens to a joint surface with the second intermediate member 35. The air passage 31 is formed. Ring-shaped grooves 33, 36 each having a semicircular cross section are formed to face each other on the joint surface of both the intermediate members 30, 35, and a donut-shaped air passage is formed by the both grooves. The other end of the air passage 31 communicates with the opening.

Further, as can be seen from FIG. 4, the second intermediate member 3
Twelve air passages 37 are formed at equal intervals circumferentially from the ring-shaped groove 36 of No. 5 through the second intermediate member 35 in the vertical direction. Therefore, the upper ends of the air passages 37 communicate with the air passages 31 through the donut-shaped passages, and the lower ends thereof are the second passages.
The lower end of the intermediate member 35, that is, the lower end of the die 10 is opened. The air passage formed by the air passage 31, the donut-shaped air passage, and the plurality of air passages 37 is
It is called an air passage.

FIG. 5 is a sectional view of the lower part of the parison extrusion die 10 taken along the arrow V-V, and as shown in FIG.
A cylindrical outer space 48 is formed between the inner hole surface 27a of the outer member 27 and the outer peripheral surface of the cylindrical portion 35b of the second intermediate member 35, and the outer peripheral surface 15a of the second inner member 15 and the cylindrical portion 3 are formed.
A cylindrical inner space 49 is formed between the inner peripheral surface 39 of the 5b and the inner peripheral surface 39. Further, in the lower part of the cylindrical portion 35b, the outer space 4
A plurality of (12 places) notches 35c are formed to connect the inner space 49 and the inner space 49, and both spaces 48 and 49 are connected to each other at the lower part of the die 10 via the notches 35c. The air passage 37 is located between the notches 35c.

Blow molding by the blow molding device configured as described above will be described below.

First, the molten resin as the parison material is injected from the first and second resin injection ports 19a and 21a of the parison extrusion die 10. The resin injected from the first resin injection port 19a is sent into the outer space 48 through the resin passages 19, 13, 22, 32, 38. On the other hand, the second resin injection port 21a
The resin injected from the inside is sent to the inside space 49 through the resin passages 21 and 14a. In this way both spaces 4
The molten resin sent to the Nos. 8 and 49 enters the notch 35c formed in the cylindrical portion 35b of the second intermediate member 35 in the lower portion of the die 10 and mixes there, and the lotus root corresponding to the lower end opening shape of the die 10 is formed. The parison 1 having a circular cross section is extruded from the lower surface of the die 10.

This parison 1 is shown in FIG.
Consists of the outer layer 2 corresponding to the outer space 48, the inner layer 3 corresponding to the inner space 49, and the partition portion 4 corresponding to the notch 35c, and the central closed cross-section chamber 6 extending in the longitudinal direction is formed in the inner layer 3. A plurality of peripheral closed cross-section chambers 7 extending in the longitudinal direction are formed between the outer layer 2 and the inner layer 3 and are partitioned by the partition portion 4 and surround the central closed cross-section chamber 6.

FIG. 1 shows the state in which the parison 1 is pushed out from the lower end of the die 1 in this way. When the parison 1 is pushed out in this way, as shown in FIG. 7A, the parison pinch 9 , 9 are rotated about the support shafts 9a, 9a, and the lower end 1a of the parison 1 is sandwiched and welded by the tip thereof to close the lower end 1a.

Then, the parison pinches 9 and 9 are returned to their original positions, and the parison 1 is further moved while supplying air into the closed cross-section chambers 6 and 7 of the parison 1 from the first and second air passages provided in the die 10. Push out. As a result, the parison 1 is bulged and pushed downward, and is positioned between the left and right dies 50 and 60 as shown in FIG. 7B.

Next, the rods 55a, 56a, 65a, 66a of the cylinder devices 55, 56, 65, 66 are extended to move the mold bodies 51, 61 in the direction of approaching each other, and as shown in FIG. The two main bodies 51, 61 are brought into contact with each other while being sandwiched in the recesses 52, 62. At the same time, the supply and discharge of air from the first and second air passages into the closed cross sections 6 and 7 are controlled to control the outer layer 2 of the parison 1.
Inflate it until it abuts the inner surfaces of the recesses 52, 62,
Moreover, the inner layer 3 is positioned at a constant distance from the outer layer 2.

FIGS. 8A and 8B show a tank 70 formed in this way, and FIG. 8B shows a shape of the tank 70 of FIG. 8A taken along a horizontal plane. The tank outer wall 71 formed from the outer layer 2 of the parison 1 has a shape of the recesses 52 and 62 of the mold bodies 51 and 61 (recesses 52 and 6).
The shape corresponds to the shape of the molding space surrounded by 2.
The inner wall 72 is formed at a constant interval from the outer wall 71, and a plurality of partition walls 73 formed by the partition portion 4 of the parison 1 partition between the walls 71, 72. A surrounding space 76 is formed. In addition, the central closed cross-section chamber 6 of the parison 1 forms the tank internal space 75,
The peripheral closed cross-section chamber 7 forms the peripheral space 76.

Thus, by blow molding with the apparatus according to the present invention shown in FIG. 1, the tank 70 having a double wall can be easily molded. Tank 7 having such a double wall
In the case of 0, even if there is a hole in one of the outer wall 71 or the inner wall 72, the liquid or the like in the tank inner space 75 does not leak due to the other wall. For example, when this is used as a fuel tank or the like. Higher safety against fuel leaks. Also, because of the air in the surrounding space 76, the heat insulation is high,
It is also a highly heat-retaining tank.

In the above, an example of molding a tank (closed container) having a double wall is shown, but the present apparatus is not limited to such molding, and by changing the mold, for example, The pipe 80 having a predetermined bending shape having a double wall as shown in FIGS. 10 and 10 can be molded. This pipe 80 has an outer wall 81 as shown.
And an inner wall 82 connected by a partition wall 83 at regular intervals
And a partition wall 83 between the walls 81 and 82.
A peripheral space 86 partitioned by is formed. Therefore, for the same reason as the tank 70, the pipe 80 is also less likely to leak liquid or the like that passes through the internal space 85 and has good heat retention.

In addition, as shown in FIG. 10, a heat insulating material may be filled in the space 86 around the pipe 80 to further enhance the heat retaining property.

In addition, by changing the shape of the bottom opening of the die,
As shown in FIG. 1, it is also possible to mold a pipe 90 which is surrounded by an outer wall 91 and whose inside is divided into a plurality of spaces 93 by a partition wall 92. Such a pipe 90
In this case, for example, it is possible to pass a different liquid or gas in each space.

C. Effect of the Invention As described above, in the present invention, the extrusion die is
The push-out end face has an opening for pushing out a cylindrical parison having a plurality of closed cross-section chambers extending in the longitudinal direction and an air injection hole for supplying / discharging (supplying / discharging) blow molding air in each closed cross-section chamber. Therefore, at the time of blow molding, one end of the molten parison extruded from the above-mentioned opening is closed, this molten parison is positioned in the molding space of the mold, and then the plurality of air injection holes formed in the parison extrusion die. The air can be supplied to or discharged from each closed cross section of the molten parison to easily form a hollow molded article having a plurality of closed cross sections and having a predetermined shape that matches the shape of the molding space of the mold. Therefore, if such blow molding is performed, the amount of air supplied to and discharged from each closed cross section of the molten parison can be controlled, and the size of each closed cross section of the hollow molded product can be arbitrarily adjusted and formed. It is possible, for example, to form the central closed cross-section chamber located at the center as the container inner space, and to supply and exhaust air to each closed cross section so as to form a space surrounding the central closed cross section chamber by a plurality of peripheral closed cross section chambers. By adjusting, the container having the double wall surrounding the central closed cross-section chamber as the container internal space can be hollow-molded. According to this blow molding, not only the molding of a container having such a double wall but also the production of a pipe having a double wall, a pipe having a predetermined bending shape divided into a plurality of passages, etc. Various applied moldings are possible.

[Brief description of drawings]

FIG. 1 is a schematic front view showing a blow molding apparatus according to the present invention, FIG. 2 is a sectional view showing a parison extrusion die used in the above apparatus, and FIGS. 3, 4, and 5 are sectional views of FIG. Arrow III-II
Sectional views showing the die along I, IV-IV and VV, FIG. 6 is a perspective view showing a parison extruded from the die, and FIGS. 7A to 7C are blow molding apparatuses according to the present invention. FIG. 8A and FIG. 8B are perspective views and cross-sectional views showing the tank molded by the blow molding, and FIGS. 9 and 10 are molded by the blow molding of the present invention. FIG. 11 is a cross-sectional view showing a different example of the pipe formed by blow molding according to the present invention. 1 ... Parison, 2 ... Outer layer 3 ... Inner layer, 6 ... Center closed section 7 ... Around closed section, 10 ... Parison extrusion die 11,15 ... Inner member 18,20,25,27 ... Outer side Member 30, 35 ... Intermediate member, 50, 60 ... Mold

Claims (4)

[Claims] 1. An opening shaped to push out a cylindrical parison having a plurality of chambers having a closed cross section extending in the longitudinal direction, and a plurality of air injection holes for supplying and discharging blow molding air into the chambers. And a mold having a molding space of a predetermined shape for receiving the molten parison extruded from the parison extrusion die. The molten parison was received in the molding space of the mold. In the state, a multi-chamber blow molding apparatus is characterized in that air is supplied to and discharged from each of the closed cross-section chambers through the air injection hole to form a hollow molded product having an outer shape corresponding to the shape of the molding space. 2. A molten parison is extruded from the opening of a parison extrusion die in which an opening having a shape that extrudes a cylindrical parison having a plurality of chambers having closed cross sections extending in the longitudinal direction is formed. While closing the opening of one end of the molten parison, the molten parison is positioned in the molding space of the mold, and from the plurality of air injection holes formed in the parison extrusion die into each closed cross section of the molten parison. Air supply and exhaust,
A multi-chamber blow molding method, which comprises molding a hollow molded article having a plurality of closed cross sections and a predetermined shape corresponding to the shape of the molding space. 3. The size of each closed cross section of the hollow molded article is controlled by controlling the amount of air supplied to and discharged from each closed cross section of the molten parison. Multi-chamber blow molding method. 4. The closed cross-section chamber comprises a central closed cross-section chamber located at the center and a plurality of peripheral closed cross-section chambers surrounding the central closed cross-section chamber. The chamber is formed as a container internal space, and the amount of air supplied and discharged into each closed cross section is controlled so as to form a space surrounding the central closed cross section chamber by the peripheral closed cross section chamber, thereby forming a container internal space. The multi-chamber blow molding method according to claim 2 or 3, wherein a container having a double wall surrounding the central closed cross-section chamber is hollow-molded.