JPH0418810Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention distributes molten resin supplied from one extruder to multiple molding heads, and molds multiple parisons simultaneously by each molding head. The present invention relates to a multi-head parison molding apparatus, in which molten resin is distributed by a branching block equipped with a resin flow path that branches into a plurality of branch flow paths. It is.

(Prior art) When molding a hollow molded product such as a liquid container using synthetic resin, the molten resin supplied from an extruder is usually extruded into a cylindrical parison using a molding head, and the parison is molded on both sides. The material is then sandwiched between molds and air is blown into the material to form the desired shape. In that case, the molten resin extruded from one extruder is generally supplied to one molding head, but if the molded product is small,
The molten resin may be distributed to multiple molding heads so that multiple parisons are molded simultaneously. In order to distribute the molten resin in this manner, a branching block is usually used which has a resin flow path that branches from one resin inlet into a plurality of branch flow paths.

4 and 5 are a cutaway plan view and a cutaway side view showing an example of such a conventional multi-head parison forming apparatus.

As is clear from these figures, this multi-head parison forming apparatus 31 has a branch block 32.
, four forming heads 33, 33, ... vertically attached to the lower part of one side, and a branch block 32.
and an adapter 34 attached to the upper surface of the other side. The extruder (not shown) is connected to this adapter 3.
The molten resin extruded by the extruder passes through the passage 34a in the adapter 34.
It is adapted to be supplied to the branch block 32 through.

The branch block 32 is provided with a vertical resin inlet 35 on its center line that communicates with a passage 34a in the adapter 34. The resin introduction port 35 communicates with a distribution channel 36 extending in the left-right direction at its lower end. Branch block 32
Further, four parallel branch channels 37, 37, . These resin inlet port 35, distribution channel 3
6, and the branch flow path 37, the branch block 3
Two resin flow paths 38 are formed. Each branch flow path 37 is provided with a flow rate adjustment valve 39 that can adjust its flow path area.

The branch flow path 37 is formed through a vertical through hole 4 provided on the center line of the housing 40 of the molding head 33.
1, respectively. A cylindrical core 42 is inserted into the through hole 41 . The upper end of the core 42 is fitted into the through hole 41 and fixed, and the lower half thereof is formed to have a slightly smaller diameter. A spiral groove 42a is formed. In this way, the core 42 and the branch block 3
2 and the housing 40 of the molding head 33, there is a spiral passage 43a communicating with the branch flow path 37.
A resin passage 43 consisting of a ring-shaped passage 43b and an annular passage 43b below the resin passage 43 is formed.

An annular die 44 is attached to the molding head 33 at the lower end of the housing 40. Further, a core 45 is supported at the lower end of the core 42 so as to be vertically adjustable. These die 44 and core 45
An annular nozzle 46 communicating with the resin passage 43 is formed between the resin passage 43 and the resin passage 43 .

The housings 40, 40, . . . of the four molding heads 33, 33, . . . are arranged side by side in close contact with each other,
Or they are designed to be formed in one piece.

In such a multi-head parison molding apparatus 31, when molten resin is extruded from the extruder, the resin is guided into the branch block 32 from the resin inlet 35 and distributed to the left and right by the distribution channel 36. be done. Then, four branch channels 37, 3
7,... through the four forming heads 33, 33,
Each is guided by... During this time, the flow rate of the resin flowing through each branch flow path 37, 37, . . . is adjusted by the flow rate adjustment valves 39, 39, .
The resin is evenly supplied to each molding head 33, 33, .

In the molding head 33, the resin is kneaded by a helical passage 43a and extruded from an annular nozzle 46 through an annular passage 43b. In this way, the four forming heads 33, 33,...
Four cylindrical parisons are molded simultaneously.

(Problems to be Solved by the Invention) However, in such a multi-head parison molding apparatus 31, there is no flow from the resin inlet 35 of the branch block 32 to the molding head 33 via the distribution channel 36 and the branch channel 37. The length of the resin channel 38 on both sides is different from that on the center side. Therefore, the resin flowing through the long resin flow paths 38 on both sides radiates more heat than the resin flowing through the short resin flow paths 38 on the center side, and the molten resin supplied to each molding head 33, 33,... A temperature difference will occur. In this way, when a temperature difference occurs in the supplied molten resin, each molding head 33, 3
3,... will result in different wall thicknesses of the parisons formed.

In addition, in the branch flow paths 37 on both sides, heat is radiated from the left and right side surfaces of the branch block 32;
Since almost no such heat radiation occurs in the branch flow path 37 on the central side, the temperature of the supplied molten resin will be lower than that of each molding head 33, 3.
Not only will each molding head 33 have a different temperature, but the molten resin supplied to each molding head 33 will also have a temperature difference in the circumferential direction. Such a problem also occurs between the resin passages 43, 43, . . . of the molding heads 33, 33, . If the molten resin in the molding head 33 has a temperature difference in the circumferential direction, the thickness of the molded parison will vary in the circumferential direction.

The present invention was developed in view of these problems, and its purpose is to equalize the temperature of the molten resin supplied to each molding head, thereby making it possible to obtain a parison with a predetermined wall thickness. It is to do so.

(Means for Solving the Problems) In order to achieve this objective, the present invention includes a resin passageway in the branching block that extends from the first branching part communicating with the extruder to the final branching part on the downstream side. He is trying to form it as a multistage branch flow path which bifurcates left-right symmetrically into a pair of branch flow paths in order at a branch part. The resin passages of the molding heads are communicated with the final branched flow paths.

A heat radiation space is provided between the final branch portions of the branch block so that the heat radiation conditions for the resin flowing through each final branch flow path are approximately equal.

(Function) With this configuration, the resin flow paths from the resin inlet of the branch block to each molding head all have the same length. Further, since the heat radiation space is provided in the center of the branch block, the heat radiation conditions for the resin flowing through each branch flow path are almost equal to each other. Therefore, the resin introduced to each molding head has almost no temperature difference. Furthermore, because of the heat dissipation space, the resin in each branch flow path is kept at an almost uniform temperature in the circumferential direction, so the resin in each molding head is also kept at an almost uniform temperature in the circumferential direction. Become.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

In the figure, Figures 1 to 3 show an embodiment of the multi-head parison forming apparatus according to the present invention, and Figure 1 is a horizontally cut plan view of the main part thereof.
FIG. 2 is a longitudinal sectional side view of the main part, and FIG. 3 is a partially cutaway front view.

As is clear from these figures, this multi-head parison forming apparatus 1 consists of a branch block 2, four forming heads 3, 3, . and an adapter 4 attached to the center of the end face. The adapter 4 has a straight tube shape, and an extruder (not shown) is connected to one end surface of the adapter 4, and the molten resin extruded by the extruder flows into the internal passage 4 of the adapter 4.
It is designed to lead to branch block 2 through a.

The branch block 2 has a thick flat plate shape, and a resin inlet 5 communicating with the internal passage 4a of the adapter 4 is provided on the center line of one end surface thereof. A resin flow path 6 is formed in the branch block 2 and is connected to the resin inlet 5. This resin channel 6 includes a pair of first branch channels 8 ₁ , 8 ₂ that branch symmetrically at a first branch portion 7 immediately after the resin inlet 5 , and a pair of first branch channels 8 ₁ , 8 _{2 .} The second branch 9 ₁ downstream of
It is constituted by a pair of second branch channels 10 ₁ , 10 ₂ , 10 ₃ , and 10 ₄ that branch symmetrically at 9 ₂ . First branch flow path 8 ₁ , 8 ₂
extends from the first branch part 7 to the left and right at an angle with respect to the center line of the branch block 2, and extends from the second branch part 9 ₁ to the left and right.
It is curved so as to be parallel to the center line near 9 ₂ , and its cross-sectional area is approximately one half of the cross-sectional area of the resin inlet 5. The second branch channels 10 ₁ to 10 ₄ also extend from the second branch portions 9 ₁ and 9 ₂ to the left and right at an angle with respect to the center line of the branch block 2, and extend parallel to the center line near each end. The branch block 2 is curved so that its end is open to the other end surface of the branch block 2. The cross-sectional area of the second branch channels 10 ₁ to 10 ₄ is about half that of the first branch channels 8 ₁ and 8 ₂ .

The left and right side surfaces of the branch block 2 are shaped to follow the first branch channels 8 ₁ , 8 ₂ and the outer second branch channels 10 ₁ , 10 ₄ . In addition, between the central part of the branch block 2, that is, the second branch parts 9 ₁ and 9 ₂ , there are first branch passages 8 ₁ and 8 ₂ and a second branch passage 1 on the central side.
A substantially diamond-shaped heat dissipation space 11 is formed surrounded by outer peripheral surfaces substantially parallel to 0 ₂ and 10 ₃ . Then, the first branch channels 8 ₁ , 8 ₂ and the second branch channel 1
By appropriately setting the wall thickness around 0 ₁ to 10 ₄ , the heat dissipation conditions around them are made almost equal to each other.

The second branch flow paths 10 ₁ to 10 ₄ are connected to respective resin passages 12, 12, . . . of the four molding heads 3, 3, . Therefore, in this embodiment, the second branch channels 10 ₁ to 10 ₄ are the final branch channels, and the second branch portions 9 ₁ and 9 ₂ are the final branch portions.

Each forming head 3 is connected to a branch block 2, respectively.
, a second housing 14 fixed to the lower surface of the first housing 13, and a third housing 15 fixed to the lower surface of the second housing 14. . The first housing 13 includes a curved portion 1 of the resin passage 12 that is connected to the second branch channels 10 ₁ to 10 ₄ of the branch block 2 and curves downward at a substantially right angle.
2a is provided. One side of the curved portion 12a is formed by the tip of a flow rate regulating valve 16 that can slide in the front-rear direction to adjust the cross-sectional area of the passage 12. By using such a flow rate adjustment valve 16, it becomes possible to significantly adjust the flow rate of the resin flowing through the passage 12.

The resin passage 12 in the second housing 14 is a linear passage 12b extending vertically through the center of the housing 14. A static mixer 17 is provided in the linear passage 12b. This static mixer 17 has a plurality of spiral blades 17a, 17a, . . . connected in series such that the ends of the blades 17a are perpendicular to each other. It is designed to be repeatedly divided and kneaded while passing through.

A core 18 is attached within the third housing 15 on its center line. Between the core 18 and the housing 15, there is an annular passage 1 communicating with the linear passage 12b of the second housing 14.
2c is formed. An annular die 19 is attached to the lower end of the third housing 15, and a core 18
An annular nozzle 21 communicating with the annular passage 12c is formed between the core 20 attached to the lower end of the annular nozzle 21 and the annular nozzle 21 communicating with the annular passage 12c.

A gap 22 is provided between the first and second housings 13, 13 and 14, 14 of adjacent molding heads 3, 3. Moreover, the distance between the third housings 15 and 15 is sufficient.

In the multi-head parison molding apparatus 1 configured as described above, when molten resin is extruded from the extruder, the resin is guided into the branch block 2 through the resin inlet 5. And the first branch part 7
, it is evenly distributed to the pair of first branch channels 8 ₁ and 8 ₂ . The resin flowing through the first branch channels 8 ₁ , 8 ₂ is transferred to a pair of second branch channels 10 ₁ , 10 ₂ and 10 ₃ , 1 in the second branch portions 9 ₁ , 9 ₂ , respectively.
0 ₄ evenly distributed. In this way, the molten resin supplied from the extruder is transferred to the four second branch channels 10.
₁ to 10 ₄ and guided to four molding heads 3, 3, . . . , respectively.

During this time, since the first branch channels 8 ₁ , 8 ₂ and the second branch channels 10 ₁ , 10 ₂ , 10 ₃ , 10 ₄ are formed symmetrically, the branch block 2
The resin flow paths 6 extending from the resin inlet 5 to the exits of the second branch flow paths 10 ₁ to 10 ₄ have the same length, and a heat radiation space 11 is provided in the center of the branch block 2 . By providing the surroundings of the first branch channels 8 ₁ and 8 ₂ and the second branch channels 10 ₁ to 10
Since the heat dissipation conditions around 10 ₄ are made equal, each branch flow path 8 ₁ , 8 ₂ and 1
The resin flowing between 0 ₁ and 10 ₄ similarly radiates heat. Therefore, the temperature of the molten resin guided to each molding head 3, 3, . . . is the same.

In the molding head 3, the molten resin is adjusted to an appropriate amount by a flow rate regulating valve 16, and then guided to a static mixer 17. In the static mixer 17, the molten resin is divided into two equal parts by the first blade 17a and kneaded, and then divided into two equal parts again by the next blade 17a and kneaded. By repeating this division and kneading, the molten resin discharged from the static mixer 17 becomes uniform throughout. That is, the temperature of the resin becomes uniform also in the circumferential direction. Moreover, there is a gap 22 between each molding head 3, 3,...
are provided and are separated from each other, so that the heat dissipation conditions in each molding head 3, 3, . . . are also the same. Therefore, there is no difference in temperature between the molten resin inside the molding heads 3, 3, . . . .

The molten resin homogenized in this way is guided to the annular passage 12c of the third housing 15, and is further extruded through the annular nozzle 21 to be formed into a cylindrical parison. As mentioned above, the molten resin is kept at approximately the same temperature in each molding head 3, 3, ..., and no temperature difference occurs in the circumferential direction. , . . . have the same wall thickness, and each has a predetermined wall thickness in the circumferential direction.

In the above embodiment, the multi-head parison molding apparatus 1 is equipped with four molding heads 3, 3, . . . , but the present invention has eight, 16
The present invention can also be applied to a multi-head parison molding apparatus having several molding heads. In that case, each of the second branch channels 10 ₁ to 10 ₄ further branches symmetrically into a pair of branch channels, and the branch channels further branch into a pair of branch channels, and so on.
All you have to do is increase the number of branches.

Further, in the above embodiment, the heat dissipation space 11 is provided only in the center of the branch block 2, but between the second branch channels 10 ₁ and 10 ₂ , 10 ₂ ,
It is also possible to provide such a heat dissipation space between 10 ₃ and between 10 ₃ and 10 ₄ .

(Effect of the invention) As is clear from the above description, according to the invention, a multi-stage branch flow path is formed in which the resin flow path provided in the branch block is symmetrically branched into a pair of branch flow paths at each branch part. Since the resin flow paths are formed by the same method, the lengths of the resin flow paths leading to each molding head are all equal. In addition, a heat dissipation space is provided between each branch channel so that the heat dissipation conditions around the branch channel are approximately equal, so that the molten resin flowing through each branch channel radiates heat in approximately the same way. become. Moreover, the temperature difference in the circumferential direction of the molten resin is also reduced.

Therefore, each molding head is supplied with molten resin at a nearly constant temperature.
Further, since the molten resin within the molding head has almost no temperature difference in the circumferential direction, it becomes possible to obtain a parison of a constant thickness using each molding head.

[Brief explanation of drawings]

FIG. 1 is a cutaway plan view of essential parts showing an embodiment of a multi-head parison forming apparatus according to the present invention, FIG. 2 is a vertical sectional side view of essential parts of the multi-head parison forming apparatus, and FIG. FIG. 4 is a partially cutaway front view of the multi-head parison forming apparatus, FIG. 4 is a partially cutaway plan view showing an example of a conventional multi-head parison forming apparatus, and FIG. FIG. 2 is a longitudinal cross-sectional side view of a main part of the type parison forming apparatus. DESCRIPTION OF SYMBOLS 1... Multi-head parison molding device, 2... Branch block, 3... Molding head, 5... Resin inlet, 6... Resin flow path, 7... First branch part, 8 ₁ ,
8 ₂ ... First branch flow path, 9 ₁ , 9 ₂ ... Second branch part (final branch part), 10 ₁ , 10 ₂ , 10 ₃ , 10 ₄ ...
2nd branch flow path (final branch flow path), 11... heat radiation space, 12... resin passage, 12b... linear passage,
13, 14, 15...Housing, 17...Static mixer, 19...Die, 20...Core,
22...Gap.

Claims (1)

[Claims for Utility Model Registration] (1) Branching block 2 equipped with a resin channel 6 that branches molten resin supplied from an extruder into a plurality of branch channels 8 ₁ , 8 ₂ , 10 ₁ to 10 ₄ A multi-head parison molding apparatus 1, in which a plurality of parisons are distributed to a plurality of molding heads 3, 3, . . . and simultaneously molded by each molding head 3, 3, . . . The resin channel 6 branches symmetrically into a pair of first branch channels 8 ₁ , 8 ₂ at a first branch part 7 communicating with the extruder, and each of the first branch channels 8 ₁ , 8 ₂ symmetrically branches into a pair of second branch channels 10 ₁ , 10 ₂ , 10 ₃ , 10 ₄ at the downstream second branch portions 9 ₁ , 9 ₂ , and branches in the same manner sequentially to reach the final branch portion 9 . ₁ , 9 ₂ branch into final branch channels 10 ₁ to 10 ₄ which communicate with the resin passages 12 , 12 , . . . of the respective molding heads 3 , 3 , . . . Final branch 9 ₁ ,
A multi-head parison molding apparatus, in which a heat radiation space 11 is formed between 9 _{and 2} to substantially equalize the heat radiation conditions of the resin flowing through each of the final branch channels 10 ₁ to 10 ₄ . (2) The resin passage 12 of each molding head 3 is provided with a linear passage 12b passing through the center of the housing 14 of the molding head 3, and a static mixer 17 is provided in the linear passage 12b. A multi-head parison forming apparatus according to claim 1 of the claimed utility model registration. (3) Housing 1 for each of the molding heads 3, 3,...
3, 13,...; 14, 14,...Gap 22 between
A multi-head parison forming apparatus according to claim 2 of the utility model registration claim, characterized in that it is provided with: