JPH0683330U - Multi-layer blow molding machine - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a multilayer blow molding machine capable of flexibly responding to a molding purpose. [Structure] When injecting outer layer resin, intermediate layer resin, and inner layer resin from a die as a multi-layer parison, an extruder and an accumulator are provided for each resin. Then, a resin passage of the manifold is provided for each of the manifolds divided into multiple layers to obtain a parison in which the resin is locally laminated in multiple layers in the thickness direction and the width direction.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a multi-layer blow molding machine.

[0002]

[Prior art]

 Generally, a resin hollow container is formed by blow molding in which pressurized air is blown into a parison inserted into a mold to form a single resin. In some cases, a multi-layer parison formed by laminating a plurality of resin layers is used to compensate for the insufficient characteristics. The cross-section of the thus laminated multi-layer parison formed a multi-layer parison having an all-round multi-layer structure for each layer.

[0003]

[Problems to be solved by the device]

 However, in the above-mentioned conventional multilayer blow molding, depending on the intended use of the molded product, for example, there may be a case where only the resin for the outer layer of the skin material is locally multilayered. In such a case, if the entire circumference is multi-layered, it is necessary to form multi-layers even in unnecessary parts, which has the drawback of increasing the amount of resin for the outer layer, and at the same time separating waste during recycling. The problem that it was impossible was also raised.

The present invention focuses on the above-mentioned conventional problems, and an object thereof is to provide a multi-layer blow molding machine capable of flexibly responding to a molding purpose.

[0005]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, a multilayer blow molding machine according to the present invention includes a die housing in a multilayer blow molding apparatus for forming a multilayer by sandwiching a resin layer for an intermediate layer with a resin layer for an inner layer and a resin layer for an outer layer. Coaxially divided split mandrels are inserted to form a plurality of resin passages, and a resin inlet from the extruder side is opened in the resin passage at a symmetrical position. A manifold is formed on the surface of the land of the mandrel, which branches to the left and right in the circumferential direction, reduces the cross-sectional area of the passage, and forms a manifold that curves in the extrusion direction. The manifold end and the manifold end from the other resin inlet are joined together. To form a long manifold, and at least one of the short manifolds does not have the confluence.

[0006]

[Action]

 According to the above configuration, the outer layer resin, the intermediate layer extruder, and the inner layer extruder are filled with the outer layer resin, the intermediate layer resin, and the inner layer resin from the respective accumulators. When the plunger is driven under pressure, the resin for the outer layer, the resin for the intermediate layer, and the resin for the inner layer pass through the long and short manifolds, respectively, and the resin flows down uniformly in each resin passage. At this time, the resin passing through the long manifold flows down from the end of the manifold and the merging portion, and the resin passing through the short manifold flows down only from the end of the manifold because there is no merging portion, and from the bottom of the die to the inside of the parison in the thickness direction from the outside to the inside. On the other hand, a multi-layer parison having a three-layer structure of a local resin for the outer layer, a resin for the intermediate layer and a resin for the inner layer, which are arranged all around, is molded.

[0007]

【Example】

 Specific embodiments of the multilayer blow molding machine according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a cross-sectional view of a main part device applied to the multilayer blow molding method according to the embodiment, and shows an extruder, an accumulator, and a parison injection die. First, the die 10 has a die housing 12 made of a rectangular block, and a through hole 14 having a substantially circular cross section is bored along the vertical center line. Such a through hole 14 is opened in the lower end surface of the die housing 12 in a state where the inner diameter is gradually reduced along the way from the middle to the lower end surface of the die housing 12.

A mandrel 16 having a diameter smaller than that of the through hole 14 is inserted into the die housing 12. The mandrel 16 includes a circular main mandrel 16c located at the center of the die 10, an inner ring mandrel 16b located at the outer periphery of the main mandrel 16c, and an outer ring mandrel 16a located at the outermost layer. It has a three-layer structure. That is, in the die housing 12, a cylindrical outer ring mandrel 16a having a diameter smaller than that of the through hole 14 is disposed, and between the outer peripheral surface of the outer ring mandrel 16a and the inner peripheral surface of the through hole 14. A resin passage 18 having a length reaching the lower end of the inner ring mandrel 16b is formed therein.

Further, the outer peripheral surface from the middle of the main mandrel 16c to the lower end surface is engraved in a circular shape to form a resin passage 20 between the inner mandrel 16b and the inner peripheral surface. Furthermore, the outer peripheral surface from the middle of the inner ring mandrel 16b to the lower end surface is engraved in a circular shape to form a resin passage 21 between the inner ring mandrel 16b and the inner peripheral surface of the outer ring mandrel 16a. Between the reduced diameter portion 14a of the through-hole 14 below the die housing 12 and the mandrel 16, a hybrid resin passage 22 having a length reaching the resin discharge port 28 is formed.

A lower end of the mandrel 16 is formed so as to be narrowed in accordance with the reduced diameter portion of the through-hole 14, and a parison control core 16d is attached to the mandrel 16 so that the mandrel 16 can move in and out. A mandrel lip 29 is integrally provided at the tip of the parison control core 16d so as to face the opening of the through-hole 14 and form a circular ring-shaped resin discharge port 28 between the opening of the through-hole 14 and the parison control core 16d. ing. Therefore, the die gap of the resin discharge port 28 can be arbitrarily changed by changing the amount of entry and exit of the parison control core 16d.

The die gap can be changed by driving the control cylinder 30 fixed to the support plate 24 standing on the die housing 12. Therefore, the control cylinder 30 and the parison control core 16d are connected to each other. The rod 32 is inserted into the main mandrel 16c.

On the other hand, the die 10 has an outer layer resin supply device 40 for supplying the outer layer resin 13a, an intermediate layer resin supply device 50 for supplying the intermediate layer resin 13b, and an inner layer for supplying the inner layer resin 13c. Each resin supply device 60 is attached. Since the resin supply devices 40, 50 and 60 have the same configuration, only the structure of the outer layer resin supply device 40 will be described, and the description of the intermediate layer resin supply device 50 and the inner layer resin supply device 60 will be omitted.

The outer layer resin supply device 40 (50, 60) includes an outer layer extruder 42 (52, 62) and an outer layer accumulator 44 (54, 64), and the die housing 12 has an outer layer accumulator 44 ( 54, 64) are attached. The accumulator 44 (54, 64) has a plunger 44a (54a, 64a) inserted therein. The outer layer accumulator is driven by driving the plunger 44a (54a, 64a) by an outer layer injection cylinder 45 (55, 65). The inner volume of 44 (54, 64) is made variable, and the injection pressure of the parison 70 is generated by pressurizing the resin 13a (13b, 13c) for the outer layer supplied inside and pressurizing it into the die 10. .

In order to feed the resin 13a (13b, 13c) for the outer layer from the accumulator 44 (54, 64) for the outer layer to the die 10, the nozzle portion 46 (56, 66) is provided at the tip of the accumulator 44 (54, 64) for the outer layer. ) Is provided, and this is flange-connected to the die housing 12, and the outer layer resin introducing passage 48 (58) to the outer layer manifold 47 (described later) formed in the outer ring mandrel 16 a (inner ring mandrel 16 b, main mandrel 16 c). , 68) and the nozzle passage 49 (59, 69) are connected. Furthermore, in order to meter the outer layer resin 13a (13b, 13c) to the outer layer accumulator 44 (54, 64), the outer layer extruder 42 (52, 62) passes through the extrusion passage 45 (55, 66). It is connected. Inside the outer layer extruder 42 (52, 62), a screw 42a (52a, 62a) is provided so as to be rotatable and movable forward and backward in a loosely fitted state.

The outer layer supplied to the outer layer resin inlet 71a (71b, 71c) from the outer layer accumulator 44 (54, 64) connection nozzle passage 49 (59, 69) provided on the peripheral wall of the die housing 12. First, the resin 13a (13b, 13c) for the outer ring is branched halfway to the left and right in the circumferential direction of the outer ring mandrel 16a (16b, 16c) to gradually decrease the cross-sectional area of the passage at a predetermined ratio and in the extrusion direction with a predetermined curvature. An outer layer manifold 47 having a semicircular cross section that is curved in a vertical direction is formed. Except for the outer layer manifold 47 which does not have the merging portion 72a, the other end of the inner layer manifold 57 and the inner layer manifold 67 are symmetrical with respect to the intermediate layer manifold 57 and the inner layer on the opposite side. It is formed so as to join between the manifolds 67 at positions of approximately 180 degrees from the resin inlets 71b and 71c for the intermediate layer and the inner layer.

The merging portions 72b and 72c are coupled so that the merging symmetric intermediate layer manifold 57 and the inner layer manifold 67 are in contact with the inner ring mandrel 16b and the main mandrel 16c, respectively, along the respective axial lines. Have been joined. As a result, the flow lines of the intermediate layer resin 13b and the inner layer resin 13c flowing down the intermediate layer manifold 57 and the inner layer manifold 67 are parallel to each other at the merging portions 72b and 72c. The outer layer resin passage 18 (20, 21) from the lower edge of the outer layer manifold 47 (57, 67) to the mixed resin passage 22 is shallower than the passage cross-sectional depth of the outer layer manifold 47 (57, 67). The land portions 75 (76, 77) that form the outer ring mandrel 16a (16b, 16c) are formed by adjusting the cutting depth of the outer periphery of the outer ring mandrel 16a (16b, 16c) as described above.

The blow molding machine having such a structure is used to form a multi-layer parison having three layers in the thickness direction, which is performed as follows.

First, while using the multilayer resin 13a (13b, 13c), the plunger 44a (54a, 64a) is retracted from the outer layer extruder 42 (52, 62) to the outer layer accumulator 44 (54, 64). Extrusion filled. Next, when the plunger 44a (54a, 64a) of the outer layer accumulator 44 (54, 64) is advanced, the melted outer layer resin 13a (13b, 13c) is transferred from the nozzle passage 49 (59, 69) to the resin introduction passage 48. The outer layer resin inflow port 71a (71b, 71c) flows in through (58, 68), and the outer layer resin 13a (13b, 13c) is branched leftward and rightward by the outer layer manifold 47 (57, 67) together with the outer layer. The outer layer resin 13a flows from the lower edge of the manifold 47 (57, 67) to the land portion 75 (76, 77) successively, and the outer layer resin 13a uniformly flows into the resin passage. The intermediate layer resin 13b and the inner layer resin 13c branch left and right at the intermediate layer manifold 57 and the inner layer manifold 67, respectively, and reach the intermediate layer resin merging portion 72b and the inner layer resin merging portion 72c.

Since the groove cross-sectional area of the outer layer manifold 47 (57, 67) is set to be gradually reduced, the pressure distribution in the circumferential direction becomes uniform, and the resin passage 18 (20, 21) is kept as it is. To reach the hybrid resin passage 22. In this hybrid resin passage 22, the outer layer resin 13a flowing down the resin passage 18 flows down on the reduced diameter portion 14a side of the through hole 14, and then flows down from the resin passage 21 on the way to the resin discharge port 28. Resin 13b flows down on outer layer resin 13a. Further, the inner layer resin 13c flowing down from the resin passage 20 near the resin discharge port 28 flows down on the intermediate layer resin 13b, so that among the outer layer resin 13a, the intermediate layer resin 13b, and the inner layer resin 13c. Only the required width is locally made as the outer layer resin 13a, and the entire circumference is made up of the intermediate layer resin 13b and the inner layer resin 13c, respectively. It is ejected from 28. The cross section of the parison 70 laminated in this way is formed as shown in FIG.

In the above description, the configuration in which only the outer ring mandrel 16a is provided with the short manifold 47 having no merging portion on the outer peripheral portion has been described, but the outer ring mandrel 16b alone does not have a merging portion on the outer peripheral portion. The short manifold 57 may be provided (not shown), or the short manifolds 47 and 57 having no merging portion may be provided on the outer circumferences of the outer ring mandrel 16a and the inner ring mandrel 16b, respectively. May be omitted. That is, in the case where a short manifold having no merging portion is provided on the outer peripheral portion of only the inner ring mandrel, the cross-section of the laminated parison 70 has an intermediate layer portion as shown in Fig. 4 (2). Only a wide width is locally formed in the intermediate layer resin 13b. When the outer ring mandrel and the inner ring mandrel are provided with short manifolds that do not have a merging portion on the outer periphery, the cross section of the laminated parison 70 is as shown in Fig. 4 (3). In addition, only the required widths of the outer layer portion and the intermediate layer portion are locally formed in the outer layer resin 13a and the intermediate layer resin 13b.

Although the parison 70 has a three-layer structure in this embodiment, it may have a single-layer structure, two-layer structure, or four-layer structure or more by increasing the number of divisions of the mandrel 16.

[0023]

[Effect of device]

 As is clear from the above description, the multi-layer blow molding machine according to the present invention is a multi-layer blow molding device that forms a multi-layer by sandwiching an intermediate resin layer with an inner resin layer and an outer resin layer. Multiple resin passages are formed by inserting split mandrels that are coaxially divided into the housing, and resin inlets from the extruder side are opened in symmetrical positions in the resin passages. On the surface of the land of the split mandrel, a manifold that branches left and right in the circumferential direction to reduce the cross-sectional area of the passage and curves in the extrusion direction is formed, and the manifold end and the manifold end from the other resin inlet are joined together. To form a long manifold, and at least one of them is formed into a short manifold without the confluent portion, so that a large number of parts are partially formed in one shot. Reduction since it is possible, it is not possible to mix the different materials (Fukuzai) the portion to be the burr becomes possible recycling. In addition, there is no resin retention area in the resin flow path inside the die head, which improves color changeability and resin changeability, and the multi-layered mandrel facilitates disassembly and installation, and cleaning during color change and resin change is facilitated. It is effective for and can flexibly deal with the diversification of the number of layers of molded products.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram of a blow molding machine showing an embodiment according to the present invention.

FIG. 2 is an enlarged sectional view of a lower part of the die.

FIG. 3 is a perspective view of an inner ring mandrel.

FIG. 4 is a cross-sectional view illustrating a formation state of a three-layer parison according to an embodiment of the present invention.

[Explanation of symbols]

10 dies 12 dies housing 13a outer layer resin 13b intermediate layer resin 13c inner layer resin 16 mandrel 16a outer ring mandrel 16b inner ring mandrel 16c main mandrel 18, 20, 21 resin passage 22 mixed resin passage 28 resin discharge port 40 (50, 50, 60) Outer layer resin supply device (intermediate layer resin supply device, inner layer resin supply device) 42 (52, 62) Outer layer extruder (intermediate layer extruder,
Inner layer extruder) 44 (54, 64) Outer layer accumulator (intermediate layer accumulator, inner layer accumulator) 44a, 54a, 64a Plunger 45, 55, 65 Extrusion passage 47 (57, 67) Outer layer manifold (intermediate layer) Manifold, inner layer manifold) 48, 58, 68 Resin introduction passage 49, 59, 69 Nozzle passage 70 Parison 71a (71b, 71c) Outer layer resin inlet (intermediate layer resin inlet, inner layer resin inlet) 72b Middle Layer resin merging portion 72c Inner layer resin merging portion 75 (76, 77) Land portion

Claims (1)

[Scope of utility model registration request] 1. A multi-layer blow molding device for forming a multi-layer by sandwiching a resin layer for an intermediate layer with a resin layer for an inner layer and a resin layer for an outer layer, wherein a plurality of mandrel coaxially divided is inserted in a die housing. A resin passage is formed, a resin inlet from the extruder side is opened in the resin passage at a symmetrical position, and each resin inlet is branched to the left and right in the circumferential direction on the land surface of the split mandrel to obtain a passage cross-sectional area. A short manifold that forms a long manifold by forming a manifold that decreases and bends in the extrusion direction, and joins the manifold end and the manifold end from the other resin inlet to form a long manifold, and at least one of which does not have the joining portion. A multi-layer blow molding machine characterized in that