JP2025010396A - Injection blow molding machine and injection molding system - Google Patents

Abstract

To provide a mold device capable of molding a container-shaped molded product having a protrusion formed on an outer surface of an opening end portion.SOLUTION: There is provided a mold device 101, comprising: an injection molding mold 111 having an injection side concave mold portion 112; a blow molding mold 121 having a blowing-side concave mold portion 122; and an intermediate mold 131 having a convex mold portion 132 that is disposed in the injection side concave mold portion 112 or the blowing side concave mold portion 122 in a mold clamped state. In the clamped state, an injection molding cavity 141 defined between the injection side concave mold portion 112 and the convex mold portion 132 has a shape corresponding to a container-shaped preform 201 having an opening end portion 203, and a blow molding cavity 151 defined between the blowing side concave mold portion 122 and the convex mold portion 132 has a shape corresponding to a container-shaped molded product 211 having an opening end portion 213 with a protrusion 215 formed on the outer surface.SELECTED DRAWING: Figure 5

Description

This invention relates to a mold device and an injection molding system used in injection blow molding.

Injection blow molding may be performed by attaching a specified mold device to an injection blow molding machine. This mold device may include an injection molding die having an injection side concave mold portion, a blow molding die having a blow side concave mold portion, and an intermediate die having a convex mold portion that is placed in the injection side concave mold portion or the blow side concave mold portion in a clamped state.

In injection blow molding using an injection blow molding machine, an injection molding cavity is defined between the injection side concave mold part and the convex mold part while the mold is clamped, and molding material is injected into this injection molding cavity to mold a preform. After that, a blow molding cavity is defined between the blow side concave mold part and the convex mold part while the mold is clamped, and the preform placed in the blow molding cavity is expanded by supplying a fluid such as air to form a molded product.

Related technologies include, for example, those described in Patent Document 1.

JP 2018-167579 A

However, in the above-mentioned injection blow molding, there is a need to be able to mold container-shaped molded products with threaded or other protruding parts on the outer surface of the opening end.

This invention is aimed at solving these problems, and its purpose is to provide a mold device and an injection molding system that can mold a container-shaped molded product with a protrusion formed on the outer surface of the opening end.

One mold apparatus capable of solving the above-mentioned problems comprises an injection molding mold having an injection side concave mold portion, a blow molding mold having a blow side concave mold portion, and an intermediate mold having a convex mold portion that is placed in the injection side concave mold portion or the blow side concave mold portion in a mold clamping state, wherein in the mold clamping state, the injection molding cavity defined between the injection side concave mold portion and the convex mold portion has a shape corresponding to a container-shaped preform having an open end, and the blow molding cavity defined between the blow side concave mold portion and the convex mold portion has a shape corresponding to a container-shaped molded product having an open end with a protrusion formed on its outer surface.
One injection molding system includes the above-mentioned mold apparatus and an injection blow molding machine to which the mold apparatus is attached.

The above mold device can be used to mold a container-shaped molded product with a protrusion on the outer surface of the opening end.

1 is a cross-sectional view showing an example of an injection blow molding machine to which a mold device according to an embodiment of the present invention can be attached, together with the mold device. 2 is a side view showing the mold opening state of the mold device of FIG. 1 and a cross-sectional view taken along line II-II of FIG. 2 is a side view showing a mold clamping state of the mold device of FIG. 1 and a cross-sectional view taken along line II-II thereof. 1 is a side view showing a molded product and a preform molded by a mold apparatus of one embodiment, with a radial half thereof separated by a central axis cut away. FIG. A cross-sectional view along the mold width direction showing the injection side concave portion of an injection molding mold, the blow side concave portion of a blow molding mold, and the convex portion of an intermediate mold provided in a mold apparatus of one embodiment. 6 is a cross-sectional view taken along the width direction of the mold, showing the injection side concave mold portion, the blowing side concave mold portion, and the convex mold portion of the mold device of FIG. 5 in a clamped state and an open state, respectively. A cross-sectional view along the mold width direction showing the injection side concave portion of an injection molding mold, the blow side concave portion of a blow molding mold, and the convex portion of an intermediate mold provided in a mold apparatus of another embodiment. 8 is a side view showing a molded product and a preform molded by the mold device of FIG. 7, with a radial half portion separated by a central axis being cut away. FIG. 8 is a cross-sectional view taken along the die width direction, showing a convex portion of an intermediate die provided in the die device of FIG. 7. 8 is an enlarged cross-sectional view of a main portion of a blow-side concave portion of a blow molding die and a convex portion of an intermediate die provided in the die device of FIG. 7. 10 is a cross-sectional view taken along the width direction of the mold, showing a modified example of a convex portion of an intermediate mold of a mold device or a concave portion of an injection side of an injection molding mold. FIG.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
The injection blow molding machine 1 illustrated in FIG. 1 is equipped with a mold apparatus 101 according to an embodiment of the present invention, and generally includes an injection device 21 that melts molding material and injects it into the mold apparatus 101, a moving device 26 that moves the injection device 21 forward and backward relative to the mold apparatus 101, and a mold clamping device 31 that has a fixed platen 32a, a movable platen 32b, and an intermediate mold support frame 32c, and opens and closes the mold apparatus 101 between a mold clamping state and a mold open state.

The injection blow molding machine 1 is used for injection blow molding. In injection blow molding, a molding material is injected into the injection molding cavity of the mold device 101 to mold a preform, and then a gas such as air or other fluid is supplied to the preform in the blow molding cavity of the mold device 101 to expand the preform and produce a molded product.

(Molding equipment)
The mold device 101 includes an injection molding mold 111 attached to the fixed platen 32a side, a blow molding mold 121 attached to the movable platen 32b side, and an intermediate mold 131 supported by an intermediate mold support frame 32c between the injection molding mold 111 and the blow molding mold 121 and rotated by a rotation shaft portion 41 of the intermediate mold support frame 32c, as shown in Figures 2 and 3.

When the mold device 101 is attached to the injection blow molding machine 1 in this manner, the injection mold 111 has an injection side concave mold portion 112 on the surface side facing the intermediate mold 131, as shown in FIG. 2(b). The blow mold 121 has a blow side concave mold portion 122 on the surface side facing the intermediate mold 131, as shown in FIG. 3(b). The intermediate mold 131 also has convex mold portions 132 on both sides of the surface facing the injection mold 111 and the surface facing the blow mold 121, which are disposed within the injection side concave mold portion 112 or the blow side concave mold portion 122 in a clamped state.

In the mold clamping state shown in FIG. 3, an injection molding cavity is defined between the injection side concave mold portion 112 and the convex mold portion 132, where molding material is injected to mold the preform 201. After the preform 201 is molded in the injection molding cavity, the mold device 101 enters the mold open state as shown in FIG. 2, and the convex mold portion 132, while holding the preform 201, is inverted with the rotation of the intermediate mold 131 by the rotating shaft portion 41 and faces the blow molding mold 121. Then, when the mold device 101 enters the mold clamping state again as shown in FIG. 3, a blow molding cavity is defined between the blow side concave mold portion 122 and the convex mold portion 132 holding the preform 201. In the blow molding cavity, the preform 201 is expanded by blowing fluid from the inside, becoming a molded product 211. When the mold device 101 is in a clamped state, such injection molding and blow molding are performed simultaneously in the injection molding cavity and blow molding cavity defined by the injection side concave mold portion 112 or the blow side concave mold portion 122 and the convex mold portions 132 provided on both sides of the injection molding die 111 side and the blow molding die 121 side.

In the illustrated example, the injection-side concave portion 112 of the injection mold 111, the convex portion 132 of the intermediate mold 131, and the blow-side concave portion 122 of the blow mold 121 are each arranged in pairs in the mold width direction and six in the height direction (the vertical direction in Figures 2(a) and 3(a)), totaling twelve portions, but the numbers can be changed as appropriate.

By the way, according to the mold device 101 of this embodiment, it is possible to mold a molded product 211 having a cylindrical container shape with a bottom as shown in FIG. 4(a). This molded product 211 is obtained by passing through a preform 201 having a cylindrical container shape with a bottom as shown in FIG. 4(b).

More specifically, the molded product 211 shown in FIG. 4(a) has a cylindrical main body 212 such as a cylinder, an open end 213 located at one end in the axial direction (left and right direction in FIG. 4) of the cylindrical main body 212, and a sealed end 214 located at the other end in the axial direction of the cylindrical main body 212 and sealed by a bottom 214a. The outer surface of the open end 213 is formed with a protruding portion 215 having a shape such as a spiral that protrudes from the outer surface and extends in the axial direction while rotating in the circumferential direction on the outer surface. When the helical protruding portion 215 is formed, it becomes possible to attach and detach a cap (not shown) having a corresponding helical groove on the inner surface by screwing the cap onto the open end 213.

In this molded product 211, the cylindrical main body 212 includes a cylindrical body 212a such as a cylinder having a constant inner and outer diameter continuing from the closed end 214, and a tapered portion 212b whose inner and outer diameters gradually decrease toward the open end 213 and connects the body 212a to the open end 213. A ring-shaped flange portion 216 such as a ring included in the above-mentioned protrusion portion 215 is formed in the portion of the open end 213 closer to the tapered portion 212b. Note that the outermost end on the axial direction outside the open end 213 is a buildup portion 217 that is slightly thicker than the open end 213 and slightly protrudes toward the outer periphery, but this buildup portion 217 is not considered to be the protrusion portion 215. Here, the region from the flange portion 216 in the axial direction to just before the outermost end on one end side is the open end 213. As long as the protrusion portion 215 is formed on the outer surface of the open end 213, the molded product 211 may have any other shape.

As shown in FIG. 4(b), the preform 201 used in the blow molding to obtain the molded product 211 has a cylindrical main body 202 whose inner and outer diameters gradually increase toward one axial end, an open end 203 located at one axial end of the cylindrical main body 202, and a sealed end 204 located at the other axial end of the cylindrical main body 202 and sealed by a bottom 204a. This preform 201 also has a padding 207 at the outermost end in the axial direction of the open end 203, but the padding 217 and 207 of the molded product 211 and the preform 201 may be omitted. The outer surface of the open end 203 of this preform 201, which does not include the padding 207, is formed smoothly.

The mold device 101 capable of molding the preform 201 and molded product 211 as described above has, in more detail, an injection mold 111, a blow mold 121, and an intermediate mold 131, as shown in FIG. 5. In the mold clamping state shown in FIG. 5, as shown in the same figure and FIG. 6(a), the convex mold part 132 on one surface side of the intermediate mold 131 is inserted and arranged in the injection side concave mold part 112 of the injection mold 111, and the injection molding cavity 141 is defined between them. At this time, the convex mold part 132 on the other surface side of the intermediate mold 131 is inserted and arranged in the blow side concave mold part 122 of the blow molding mold 121, and the blow molding cavity 151 is defined there. Note that the preform 201 and the molded product 211 are omitted from the illustration.

The injection molding cavity 141 is a space having a shape corresponding to the shape of the container-shaped preform 201 having the open end 203 described above. The blow molding cavity 151 is a space having a shape corresponding to the shape of the container-shaped molded product 211 having the open end 213 with the protrusion 215 formed on the outer surface, also as described above.

Of these, in the blow molding cavity 151, on the inner peripheral surface of the blow-in side concave portion 122 that corresponds to the outer surface of the molded article 211, a recessed portion 123 corresponding to the protrusion portion 215 is formed at a location corresponding to the outer surface of the opening end 213 of the molded article 211, as can be seen from Figures 5 and 6. As a result, when the preform 201 held around the convex portion 132 in the blow molding cavity 151 expands due to the supply of fluid and is pressed against the inner peripheral surface of the blow-in side concave portion 122, the recessed portion 123 forms a protrusion portion 215 having a shape corresponding to the shape of the recessed portion 123 on the outer surface of the opening end 213 of the molded article 211. In this example, a helical protrusion 215 is formed on the outer surface of the open end 213 of the molded product 211, and a helical recess 123 is provided on the inner surface of the blow-in side concave portion 122 in correspondence with the protrusion 215, extending on the inner surface of the blow-in side concave portion 122.

The structure and shape of each mold of the mold device 101 can be changed as appropriate, but in the illustrated example, the injection molding mold 111 has a mold body 113 and a concave partition member 114 inserted and attached to the surface side of the mold body 113 facing the intermediate mold 131 side, as shown in FIG. 5. The concave partition member 114 has a bottomed cylindrical shape with a larger inner and outer diameter at the part exposed from the mold body 113 than the part inserted into the mold body 113. The injection side concave mold portion 112 is provided inside this concave partition member 114. The surface area of the inner peripheral surface of the injection side concave mold portion 112 corresponding to the outer surface of the opening end 203 of the preform 201 is formed smoothly. The concave partition member 114 provided with the injection side concave mold portion 112 does not have a split mold.
The injection side concave mold portion 112 is connected to the nozzle 22b of the cylinder 22 of the injection device 21 through a gate 115 provided at the deepest part of the injection side concave mold portion 112 in the concave partition member 114. As a result, during injection molding, molten molding material is supplied from the cylinder 22 to an injection molding cavity 141 defined in the injection side concave mold portion 112.

The intermediate mold 131 has a core seat 131a, such as a plate-like one, attached to the rotating shaft 41, an annular base 134 provided on the core seat 131a, and a protruding portion 135, which is inserted into and attached to the base 134, protrudes from the base 134, and has an outer diameter that gradually decreases toward the tip. The protruding portion 135 has a curved tip surface. The base 134 and the protruding portion 135 form the convex portion 132.
5, in the mold clamped state, the step 114a on the inner periphery of the portion of the concave partition member 114 exposed from the mold body 113 is aligned with the step 134a on the outer periphery of the base 134 of the intermediate mold 131. Also, here, a space that forms the build-up portion 207 of the preform 201 is defined between the annular groove 136 provided on the surface of the base 134 on the injection mold 111 side and the step 114a of the concave partition member 114.

In this embodiment, the blow molding die 121 has a split die 124 that can be opened and closed in the die width direction. This allows the molded product 211, which has a larger bottom 214a in the axial direction, to be easily removed from the blow-side concave portion 122. A split die opening and closing mechanism 62, which will be described later, defines a blow-side concave portion 122 shaped according to the outer shape of the molded product 211 inside the closed split die 124 as shown in Figures 5 and 6. A step 124a that matches the step 134a of the base 134 is provided at the portion of the split die 124 that comes into contact with the base 134 of the intermediate die 131 in the clamped state.

In the mold device 101 as described above, during blow molding, the opening end 203 of the preform 201 is pressed against the recessed portion 123 provided on the inner peripheral surface of the blow-in side concave mold portion 122 by supplying fluid to the inside, as shown in FIG. 5, to form a protruding portion 215 of the opening end 213 of the molded product 211. At this time, a part of the molding material of the opening end 203 of the preform 201 fills the recessed portion 123, which may cause a sink mark to form on the inner surface of the opening end 213 of the molded product 211. Such a molded product 211 may have insufficient strength at the opening end 213 where a cap or the like can be attached, resulting in poor quality.

To prevent this, as in the embodiment shown in FIG. 7, it is preferable to provide the injection molding cavity 341 with a thickening space 342 in which the space is partially widened at least in a part corresponding to the opening end 403 of the preform 401 shown in FIG. 8(b). Due to the thickening space 342, the preform 401 molded in the injection molding cavity 341 has a thickened part 408 in which the thickness is partially increased compared to other parts such as the cylindrical main body part 402 at least in a part of the opening end 403. When blow molding is performed using this preform 401, in the blow molding cavity 351, a part of the molding material of the opening end 403 of the preform 401 is filled into the recessed part 323 of the blowing side concave part 322, but since the extra thick part 408 is formed at the opening end 403, the occurrence of sink marks on the inner surface of the opening end 413 is suppressed in the molded product 411 obtained thereafter. As a result, it is possible to effectively prevent insufficient strength and poor quality at the opening end 413 of the molded product 411.

In the embodiment shown in FIG. 7, in order to provide the thickening space 342 as described above, a concave portion 337 is formed on the outer peripheral surface of the convex portion 332 (more specifically, the protruding portion 335) of the intermediate mold 331 at a location corresponding to the opening end 403 of the preform 401, as shown in an enlarged view in FIG. 9. Providing the thickening space 342 by forming the concave portion 337 on the convex portion 332 side in this manner is preferable in that there is no risk of undercutting the preform 401 held by the convex portion 332 on the intermediate mold 331 side when the injection molding die 311 moves from the clamped state to the mold open state in which it is separated from the intermediate mold 331. In this preform 401, a thickening portion 408 including a protruding portion 409 protruding from its inner surface is formed at the opening end 403.

Although it depends on the shape of the protrusion 415 provided on the outer surface of the opening end 413 of the molded product 411, it is preferable to form the concave portion 337 on the outer peripheral surface of the convex portion 332 over its entire circumference. This makes it possible to effectively prevent sink marks from occurring on the inner surface of the opening end 413 of the molded product 411 over the entire circumference.

Here, a spiral concave portion 337 that extends in the axial direction while rotating in the circumferential direction on the outer surface is formed on the outer peripheral surface of the convex mold portion 332 of the intermediate mold 331 in correspondence with a protrusion portion 415 such as a spiral screw portion provided on the outer surface of the opening end 413 of the molded product 411. In this case, a spiral protrusion 409 is formed on the inner surface of the thick portion 408 of the opening end 403 of the preform 401. The thick portion 408 including such a spiral protrusion 409 provides good filling of the molding material into the spiral recessed portion 323 of the blow-side concave mold portion 322 during blow molding in the blow molding cavity 351, and functions to more effectively suppress the occurrence of sink marks on the inner surface of the opening end 413 of the molded product 411. In this example, in addition to the spiral concave portion 337 described above, the outer peripheral surface of the convex portion 332 also has a tubular flange portion 416 provided on the outer surface of the opening end 413 of the molded product 411, and a corresponding annular concave portion that corresponds to the annular recessed portion of the blowing side concave portion 322.

When providing the concave portion 337 on the outer peripheral surface of the convex mold portion 332, it is preferable that the formation region Rp of the concave portion 337 on the outer peripheral surface of the convex mold portion 332 and the formation region Rd of the recessed portion 323 on the inner peripheral surface of the blow-in side concave mold portion 322 overlap at least partially in the axial direction (left and right direction in FIG. 10) in the blow molding cavity 351, as shown in the enlarged view in FIG. 10. This is because the recessed portion 323 of the blow-in side concave mold portion 322 is effectively filled with the molding material by the raised portion 409 formed on the outer surface of the opening end 403 of the preform 401 by the recessed portion 337 of the convex mold portion 332. More preferably, in the axial direction of the blow molding cavity 351, a concave portion 337 is provided on the outer peripheral surface of the convex portion 332 in a forming region Rp equal to or larger than the forming region Rd of the recessed portion 323 of the blow-side concave portion 322 so that the entire forming region Rd is covered. Other dimensions such as the depth of the recessed portion 337 of the convex portion 332 can be appropriately determined depending on the protrusion 415 provided on the opening end 413 of the molded product 411, the dimensions of the recessed portion 323 of the blow-side concave portion 322, etc.

7 has a spiral recessed portion 337 on the outer circumferential surface of the convex portion 332, but the shape of the recessed portion 337 is not limited to this. For example, in the convex portion 532 shown in FIG. 11(a), a ring-shaped recessed portion 537 is provided on the outer circumferential surface of the convex portion 532, which corresponds to the inner surface of the open end of the preform, and is recessed over a certain area in the axial direction and goes around in the circumferential direction. Such a recessed portion 537 may provide a wall thickness forming space 542.
Although not shown in the figures, it is possible to provide various protrusions, not just spiral ones, on the outer peripheral surface of the opening end of the molded product, and the shape of the recessed portion formed in the blowing side concave portion can be changed accordingly.

In addition to or instead of forming a concave portion on the outer circumferential surface of the convex mold portion, a concave portion 637 of any shape can be formed on the inner circumferential surface of the injection-side concave mold portion 612 of the injection molding die 611, as shown in FIG. 11(b). This also results in the injection molding cavity having a thickening space 642, making it possible to form thick portions in the preform.

The mold device 101 as described above can be attached to the injection blow molding machine 1 and replaced as appropriate depending on the shape of the molded product to be manufactured. For this reason, the mold device 101 is not included in the injection blow molding machine 1 and is considered to be a separate device from the injection blow molding machine 1. An apparatus that includes the injection blow molding machine 1 and the mold device 101 attached to the injection blow molding machine 1 is referred to as an injection molding system here.

(Mold clamping device)
The mold device 101 as described above is attached to the mold clamping device 31 of the injection blow molding machine 1. The mold clamping device 31 has a mold holding mechanism 32 having a fixed platen 32a, a movable platen 32b, and an intermediate mold support frame 32c, an intermediate mold moving mechanism 61 that moves the intermediate mold support frame 32c relative to the fixed platen 32a, a platen moving mechanism 33 that moves the movable platen 32b relative to the fixed platen 32a, and a split mold opening and closing mechanism 62 that opens and closes a split mold 124 of the blow molding mold 121. The intermediate mold moving mechanism 61 and the split mold opening and closing mechanism 62 will be described later with reference to FIGS. 2 and 3.

The mold holding mechanism 32 includes a fixed platen 32a located between the injection device 21 and the mold device 101, a movable platen 32b located between the fixed platen 32a and the mold device 101 and capable of moving toward and away from the fixed platen 32a, and an intermediate mold support frame 32c located between the fixed platen 32a and the movable platen 32b and capable of moving toward and away from the fixed platen 32a. The mold clamping device 31 is also provided with one or more tie bars 32d that extend from the fixed platen 32a toward the rear platen 34 described below and connect the fixed platen 32a and the rear platen 34. In this example, the movable platen 32b and the intermediate mold support frame 32c are guided by the tie bars 32d in their moving toward and away from the fixed platen 32a, but there are also cases where they are not guided by the tie bars 32d.

Of the mold holding mechanism 32, the fixed platen 32a is fixedly attached to the base frame 2. On the other hand, the movable platen 32b and the intermediate mold support frame 32c are each placed on a guide member 32e laid on the base frame 2, and can slide independently of each other in a direction away from and toward the fixed platen 32a.

In addition, at the position where the movable platen 32b and the intermediate mold support frame 32c are separated from the fixed platen 32a, the blow molding mold 121 and the intermediate mold 131 of the mold device 101 are in a mold open state in which they are open from the injection molding mold 111. By moving the movable platen 32b and the intermediate mold support frame 32c toward the fixed platen 32a from this separated position, the blow molding mold 121 and the intermediate mold 131 are in a mold closed state in which they are closed against the injection molding mold 111, and further, by moving the movable platen 32b and the intermediate mold support frame 32c toward the fixed platen 32a, the blow molding mold 121 and the intermediate mold 131 are in a mold clamped state in which they are pressed against the injection molding mold 111. Here, the direction approaching the fixed platen 32a to which the injection molding mold 111 of the mold device 101 is attached is the front side, and the direction moving away from the fixed platen 32a is the rear side. For most parts of the mold clamping device 31, except for the fixed platen 32a, the right side in FIG. 1, which is closer to the fixed platen 32a, is the front side, and the left side, which is farther away from the fixed platen 32a, is the rear side.

The illustrated intermediate mold support frame 32c has a rectangular or other frame shape when viewed from the front, and is provided with a rotating shaft portion 41 that is rotatably mounted and extends in the mold width direction (vertical direction in Figs. 2(b) and 3(b)) perpendicular to the front-rear direction in a plane parallel to the horizontal plane. The intermediate mold 131 is attached to the rotating shaft portion 41 and supports it. In this example, the axial direction of the rotating shaft portion 41 is parallel to the horizontal direction, but the axial direction of the rotating shaft portion is not limited to this, and it is also possible to set it to, for example, parallel to the vertical direction. A vertical injection blow molding machine may also be used.

The intermediate mold support frame 32c is provided with an intermediate mold rotation mechanism that rotates the rotating shaft 41 and rotates the intermediate mold 131. Although not shown, this intermediate mold rotation mechanism can be a motor or the like provided on the intermediate mold support frame 32c. A cylindrical member 42 is provided around the rotating shaft 41 between the intermediate mold 131 and the intermediate mold support frame 32c.

The intermediate mold moving mechanism 61 that moves the intermediate mold support frame 32c relative to the fixed platen 32a can be configured, for example, as shown in Figures 2 and 3, with hydraulic cylinders 61a and piston rods 61b attached to the fixed platen 32a and intermediate mold support frame 32c, respectively, and operated by a hydraulic pump driven by a motor. In this example, two pairs of hydraulic cylinders and piston rods are provided located outside the injection molding die 111 and intermediate mold 131 in the die width direction, but one pair or three or more pairs may be provided. Although not shown, the intermediate mold moving mechanism may move the intermediate mold support frame forward and backward relative to the movable platen by attaching hydraulic cylinders or the like to the movable platen instead of the fixed platen.

As shown in FIG. 1, the platen movement mechanism 33 of the mold clamping device 31 includes a rear platen 34 arranged on the base frame 2, a mold clamping motor 35 provided on the rear platen 34, a motion conversion mechanism 36 that converts the rotational motion of the mold clamping motor 35 into linear motion in the displacement direction of the movable platen 32b, and a toggle mechanism 37 that amplifies the force transmitted to the motion conversion mechanism 36 and transmits it to the movable platen 32b.

The motion conversion mechanism 36 can be various mechanisms capable of converting rotational motion into linear motion, but in this example, it is configured to include a screw shaft 36a that is driven to rotate by the mold clamping motor 35, and a nut 36b that screws onto the screw shaft 36a. The motion conversion mechanism 36 can also be a ball screw. The toggle mechanism 37 that increases the transmission force from the motion conversion mechanism 36 is configured by connecting a plurality of links 37a to 37c that connect the nut 36b of the motion conversion mechanism 36 to the movable platen 32b with joints so that they can swing. The number and shape of the links and joints can be changed as appropriate, but as shown in FIG. 1, a pair of link groups consisting of links 37a to 37c located above and below the crosshead 37d are swingably connected to the crosshead 37d that is connected to the nut 36b and extends in the vertical direction.

In addition to the above-mentioned mold clamping motor 35, a mold thickness adjustment motor 38 can also be provided on the rear platen 34. This mold thickness adjustment motor 38 functions to adjust the distance between the fixed platen 32a and the rear platen 34 movably mounted on the base frame 2 by applying a rotational driving force to the screw shaft and nut connected to the extension of each tie bar 32d of the above-mentioned mold holding mechanism 32. This makes it possible to adjust the mold thickness so that the mold device 101 can be given the desired mold clamping force even when the mold device 101 is replaced or the thickness of the mold device 101 is changed due to temperature change. Although not shown in the figure, the mold thickness can be adjusted even if the fixed platen side is movable on the base frame 2 and the rear platen side is fixed.

As shown in Figures 2 and 3, the mold clamping device 31 is equipped with a split mold opening/closing mechanism 62 that has a piston rod 62a and a hydraulic cylinder 62b, etc., and that drives the split mold 124 of the blow molding mold 121 forward and backward in the mold width direction to open and close it. The split molds 103b of the blow molding mold 121 that are moved in the same direction in the mold width direction by the split mold opening/closing mechanism 62 can be connected to each other by split mold connecting members 63a, 63b.

The illustrated mold clamping device 31 is a horizontal type in which the moving direction of the movable platen 32b is parallel to the horizontal direction, but it can also be a vertical type in which the moving direction is vertical.

(Injection unit)
The injection device 21 mainly includes a cylinder 22 having a cylindrical shape or the like extending toward the mold device 101, a screw 23 arranged inside the cylinder 22 with its central axis parallel to the cylinder 22 and with flights spirally provided around it, a heater 24 having a band shape or the like arranged around the outer periphery of the cylinder 22, and a motor box 25 arranged behind the cylinder 22 and the screw 23. Although not shown in the figure, the motor box 25 includes a metering motor that rotates the screw 23 around the central axis to accumulate a predetermined amount of molding material at the tip of the cylinder 22, an injection motor that moves the screw 23 forward and backward in each direction toward and away from the mold device 101, a pressure detection sensor that detects the pressure that the screw 23 receives from the molding material, and the like.

Note that, here, the direction approaching the fixed platen 32a of the clamping device 31 to which the injection molding die 111 of the mold device 101 is attached is defined as the front side, and the direction moving away from the fixed platen 32a is defined as the rear side. Therefore, in FIG. 1, when looking at the injection device 21 located to the right of the fixed platen 32a, the left direction approaching the fixed platen 32a is the front side, and the right direction moving away from the fixed platen 32a is the rear side.

The cylinder 22 is provided with a supply port 22a at the rear, in front of the motor box 25, to which a hopper can be attached for feeding molding material into the cylinder 22. In addition, a nozzle 22b with a smaller cross-sectional area at the front side is provided at the tip of the cylinder 22 close to the mold device 101. A water-cooled cylinder 22c for water cooling or the like can be provided near the supply port 22a.

The heater 24 arranged around the cylinder 22, including around the nozzle 22b, can be divided into multiple parts in the cylinder axial direction, for example as shown in the figure, so that the inside of the cylinder 22 inside each heater part can be heated at different temperatures. Each heater part can be provided with a temperature detector.

A backflow prevention ring (not shown) may be placed around the tip of the screw 23, which is formed by partially reducing its outer diameter, to prevent the molding material that has been sent forward and backward with the screw 23 from flowing back toward the rear. This backflow prevention ring displaces back and forth relative to the screw 23 depending on the pressure it receives from molding material located forward or rearward, thereby allowing only the flow of molding material from the rear to the front.

According to the injection device 21 having such a configuration, the molding material fed into the cylinder 22 from the supply port 22a is heated by the heater 24 on the outer periphery of the cylinder 22, melted by the rotation of the screw 23 driven by the metering motor, and sent forward inside the cylinder 22 to accumulate at the tip of the cylinder 22. At this time, the screw 23 is displaced backward by the injection motor to form a space at the tip of the cylinder 22 where the molding material can accumulate.

Then, by displacing the screw 23 forward, the molding material at the tip of the cylinder 22 is injected toward the mold device 101 through the nozzle 22b. After that, pressure is applied to the molding material filled in the cavity of the mold device 101 through the molding material remaining at the tip of the cylinder 22, performing pressure retention. At this time, it is possible to replenish the molding material that has become insufficient in the injection molding cavity of the mold device 101 due to the cooling contraction of the molding material.

Although this injection blow molding machine 1 is an in-line screw type, it is also possible to make it a pre-plasticization type injection molding machine in which the plasticizing cylinder and plasticizing screw are structurally and functionally separated from the injection cylinder and injection plunger.

(Mobile device)
The moving device 26 is provided, for example, below the motor box 25 of the injection device 21, and is an advance/retract drive mechanism for moving the injection device 21 forward and backward relative to the fixed platen 32a.
Various mechanisms can be adopted as the forward and backward drive mechanism that constitutes the moving device 26, but the moving device 26 shown in the figure is composed of a hydraulic pump 27 or the like, a pump operation motor 28, which is electric or the like, that operates the hydraulic pump 27, and a double-acting hydraulic cylinder 29 that receives hydraulic fluid from the hydraulic pump 27 and causes a piston rod, the tip of which is fixed to a fixed platen 32a, to perform an extrusion and retraction movement.

The moving device 26 further includes a slide base 26a to which the above-mentioned hydraulic pump 27, pump actuation motor 28, and hydraulic cylinder 29 are attached, and a guide 26b that is laid on the base frame 2 and guides the linear motion of the slide base 26a. This allows the forward and backward displacement of the injection device 21 placed on the top of the slide base 26a.

The moving device 26 makes it possible to move the injection device 21 away from the mold device 101, or to bring the injection device 21 closer to the mold device 101 and press the nozzle 22b of the cylinder 22 of the injection device 21 against the mold device 101 with a predetermined pressure, a so-called nozzle touch.

(Operation of injection molding machine)
The injection blow molding machine 1 described above operates to carry out the following steps.
With the mold device 101 in the mold open state shown in Figure 2, a mold closing process is performed in which the platen moving mechanism 33 moves the movable platen 32b toward the fixed platen 32a, and the intermediate mold moving mechanism 61 moves the intermediate mold support frame 32c toward the fixed platen 32a.

Next, with a predetermined amount of molding material already stored and placed inside the injection unit 21 by measuring during the previous molding, which will be described later, a clamping process is performed in which the mold unit 101 is clamped using the clamping unit 31 as shown in FIG. 3. In the clamping process, an injection molding cavity 141 is defined between the injection molding die 111 and the intermediate die 131, and a blow molding cavity 151 is defined between the blow molding die 121 and the intermediate die 131.

Then, the screw 23 advances to inject the molding material toward the injection molding cavity 141 of the mold device 101, and the injection process is performed to fill the injection molding cavity 141 with the molding material. In the injection process, after the injection molding cavity 141 is filled with the molding material, the screw 23 advances further to hold the molding material inside the tip of the injection device 21 at a predetermined pressure. Thereafter, the molding material filled in the injection molding cavity 141 is cooled and solidified. As a result, the preform 201 is molded in the injection molding cavity 141. At this time, the molding material separately charged into the injection device 21 is melted while being sent toward the tip of the injection device 21 by the rotation of the screw 23 under heating by the heater 24, and a predetermined amount of the molding material is measured and placed at the tip.

In parallel with the above-mentioned injection process, a blowing process is carried out in the blow molding cavity 151. A preform 201 that has already been molded in the injection molding cavity 141 before the intermediate mold 131 is inverted is placed in the blow molding cavity 151. In the blowing process, a fluid such as air or other gas is supplied to the preform 201, causing the preform 201 to expand in the blow molding cavity 151, and forming a molded product 211.

Then, the platen movement mechanism 33 and intermediate mold movement mechanism 61 of the mold clamping device 31 are operated to move the movable platen 32b and the intermediate mold support frame 32c away from the fixed platen 32a, and the mold opening process is performed to open the mold device 101.

After the mold opening step, the split mold opening/closing mechanism 62 is used to open the split mold 124 of the blow molding die 121 to remove the molded product 211, and then the split mold opening/closing step is performed to close the split mold 124 of the blow molding die 121.
Also, here, an intermediate mold rotating step is performed in which the intermediate mold 131 is inverted by the intermediate mold rotating mechanism. As a result, the convex mold portion 132 of the core mold of the intermediate mold 131 on the side from which the molded product 211 was collected in the split mold opening and closing step faces the injection side concave mold portion 112 of the injection molding mold 111. On the other hand, the convex mold portion 132 of the core mold of the intermediate mold 131 on the side from which the preform 201 was molded in the injection step faces the blow side concave mold portion 122 of the blow molding mold 121 while holding the preform 201.
The intermediate mold rotating step can be performed at approximately the same time as the split mold opening and closing step, or before or after the split mold opening and closing step.

In injection molding using the injection blow molding machine 1, the above-mentioned mold closing process, mold clamping process, injection process, blowing process, mold opening process, split mold opening/closing process, and intermediate mold rotation process are repeated.

REFERENCE SIGNS LIST 1 injection blow molding machine 2 base frame 21 injection device 22 cylinder 22a supply port 22b nozzle 22c water-cooled cylinder 23 screw 24 heater 25 motor box 26 moving device 26a slide base 26b guide 27 hydraulic pump 28 pump operation motor 29 hydraulic cylinder 31 mold clamping device 32 mold holding mechanism 32a fixed platen 32b movable platen 32c intermediate mold support frame 32d tie bar 32e guide member 33 platen moving mechanism 34 rear platen 35 mold clamping motor 36 motion conversion mechanism 36a screw shaft 36b nut 37 toggle mechanism 37a to 37c link 37d crosshead 38 mold thickness adjustment motor 41 rotating shaft portion 42 cylindrical member Description of the Reference Signs 61 Intermediate mold moving mechanism 61a Hydraulic cylinder 61b Piston rod 62 Split mold opening/closing mechanism 62a Piston rod 62b Hydraulic cylinder 63a, 63b Split mold connecting member 101 Mold device 103b Split mold 111, 311, 611 Injection molding mold 112, 312, 612 Injection side concave mold portion 113, 313 Mold body 114, 314 Concave partition member 114a Step portion 115, 315 Gate 121, 321 Blow molding mold 122, 322 Blow side concave mold portion 123, 323 Depression portion 124, 324 Split mold 124a Step portion 131, 413 Intermediate mold 131a, 331a Core seat 132, 332, 532 Convex portion 134, 334 Base portion 134a Step portion 135, 335 Protruding portion 136 Annular groove portion 337, 537, 637 Concave portion 141, 341 Injection molding cavity 342, 542, 642 Wall thickness forming space 151, 351 Blow molding cavity 201, 401 Preform 202, 402 Cylindrical main body portion 203, 403 Open end portion 204, 404 Closed end portion 204a, 404a Bottom portion 207, 217 Overlay portion 211, 411 Molded product 212, 412 Cylindrical main body portion 212a Body portion 212b Tapered portion 213, 413 Open end portion 214, 414 Sealed end 214a, 414a Bottom 215, 415 Projection 216, 416 Flange Rd Region where recessed portion is formed in blowing side concave portion Rp Region where concave portion is formed in convex portion

Claims (10)

an injection molding die having an injection side concave portion;
A blow molding die having a blow-side concave portion;
and an intermediate mold having a convex mold portion that is disposed in an injection side concave mold portion or an injection side concave mold portion in a mold clamping state,
In a mold clamping state, the injection molding cavity defined between the injection side concave mold portion and the convex mold portion has a shape corresponding to a container-shaped preform having an open end, and the blow molding cavity defined between the blow side concave mold portion and the convex mold portion has a shape corresponding to a container-shaped molded product having an open end with a protrusion formed on its outer surface. The mold apparatus according to claim 1, wherein the inner peripheral surface of the blowing-side concave mold portion has a recessed portion corresponding to the protruding portion at a location corresponding to the outer surface of the opening end of the molded product. The mold apparatus according to claim 1 or 2, wherein the injection molding cavity has a wall thickness forming space that partially increases the thickness of the opening end of the preform in at least a portion of the cavity. The mold apparatus according to claim 3, wherein the outer peripheral surface of the convex mold portion has a concave portion recessed from the outer peripheral surface at a location corresponding to the inner surface of the opening end of the preform. The mold device according to claim 4, wherein the concave portion is formed around the entire outer periphery of the convex portion. The mold apparatus according to claim 4 or 5, wherein the recessed portion is a spiral extending on the inner peripheral surface of the blow-in side concave mold portion, and the concave portion is a spiral extending on the outer peripheral surface of the convex mold portion. The mold apparatus according to any one of claims 4 to 6, wherein in the blow molding cavity, the region where the concave portion is formed on the outer peripheral surface of the convex mold portion and the region where the recessed portion is formed on the inner peripheral surface of the blow-in side concave mold portion overlap at least partially in the axial direction. The mold apparatus according to any one of claims 4 to 7, wherein the surface area of the inner peripheral surface of the injection side concave mold portion that corresponds to the outer surface of the opening end of the preform is smooth. The mold device according to any one of claims 1 to 8, in which, among the injection mold, blow mold, and intermediate mold, only the blow mold has a split mold. An injection molding system comprising the mold apparatus according to any one of claims 1 to 9 and an injection blow molding machine to which the mold apparatus is attached.