JPH1142670A - Multi-stage molding method of hollow molded article and injection molder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the multi-stage molding method of a hollow molded article, with which easy and smooth positioning and movement relative to respective molds can be realized, and can save the space for the injection molding, its controlling operation is easy and the multi-stage molding of the hollow molded article can be performed at low cost, and an injection molder for executing the above-mentioned method. SOLUTION: By injecting molten resin from a first injection unit in cavities, which are respectively provided on a fixed mold side and on a movable mold side through an intermediate mold 14 between the fixed mold 10 and the movable mold 12, the split bodies of a hollow molded article linkable to each other are respectively formed. Next, after the intermediate mold is retreated by opening the mold, the fixed mold and the movable mold are closed together as the intermediate mold is retreated, the split bodies of the hollow molded body are bonded. Further, molten resin is injected from a second injection unit 28 to a cavity formed at the surroundings of the bonding part of the split bodies so as to mold a hollow molded article, the split bodies of which are linked together.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding machine for molding a hollow molded product, and more particularly, to a multi-stage molding of a hollow molded product by disposing an intermediate mold between a fixed mold and a movable mold. The present invention relates to a molding method and an injection molding machine for performing the method.

[0002]

2. Description of the Related Art Conventionally, when molding plastic products, techniques such as air blow molding (injection blow molding) and injection blow molding are known as means for producing hollow molded articles. Also, using two molding machines,
There is also known a technique in which each half of a molded product is formed and these are combined in another process.

However, when a large product consisting of a closed hollow member requiring strength is required, half of each molded product is formed by the latter two molding machines, and lamination is not performed in a later process. No. In order to automate the post-process, a device for automatically setting each half of a molded product to be joined, a device for automatically injecting a resin or an adhesive into a joint, and the like are required.

As described above, for example, a divided body of a hollow molded article is formed of different resin materials using two molding machines, and then a resin material is mutually fused to a butt portion of the divided bodies. Thus, different kinds of hollow molded articles having a hollow portion therein can be molded. However, according to such a molding method, since two molding machines are required, equipment costs increase, and Since an operation of joining but joining the divided bodies formed by the respective molding machines is required, there is a problem that the number of operation steps is increased and the molding cost is increased.

From such a viewpoint, conventionally, for example, as a molding method for integrally molding a first molded article and a second molded article, a center injection molding method and a parting injection molding method are combined. Thus, a multilayer molding method has been proposed which can be molded into a multilayer using an existing molding machine and can reduce the molding cost (JP-A-62-152822).

That is, this multi-layer molding method has been proposed as a multi-color molding method. In contrast to a movable plate supported on a fixed support plate provided on a main body frame so as to be movable in the vertical direction, a movable plate is provided. Is moved to the upper limit position, the first female mold attached to a position corresponding to the male mold attached to the movable side support plate movably supported by the main body frame, and the movable platen moves to the lower limit position. When the movable platen is moved upward or downward among the second female molds attached to a position corresponding to the male mold when moved, one of the female molds is opposed to the male mold. After tightening, a first molding step of injecting a resin material from the first injection device into a molding space of one of the female mold and the male mold to form a first molded product; After opening the mold and the male mold, move the movable platen downward or upward Moving, after the first female mold holding a molded product of the other female mold and mold clamping are opposed,
A resin material is injected into the molding space between the male mold and the other female mold from the second injection device to integrally mold the second molded product with the first molded product held in the male mold. A second molding process, wherein one of the first injection device and the second injection device has an axis in a direction coinciding with the center of the machine, and is mounted on the body frame with a center injection type. And the other injection device has an axis in a direction perpendicular to the one injection device, and is a parting injection type arranged on the side of the main body frame according to the mating surface of the male mold and the female mold. Of the injection device.

Further, conventionally, the divided bodies each having a concave portion formed of a different resin material are efficiently joined and integrated so as to have a hollow portion therein, thereby reducing the molding cost. A method of forming a hollow molded article configured to obtain a hollow molded article has been proposed (JP-A-9-70855).
No.).

[0008] That is, the method of molding this hollow molded article is as follows:
A first mold movably mounted on the fixed side is provided with a core corresponding to one of the divided bodies and a cavity corresponding to the other divided body of the hollow molded product, and a movable second mold. A cavity and a core opposed to the core and the cavity of the first mold, and the first clamped mold is provided.
A first resin material is center-injected from a first injection device attached to a fixed side into a first molding space including one core and a cavity in the mold and the second mold, and After the second resin material is part-injected from the second injection device arranged on the side of the molding machine into the second molding space including the other core and the cavity, and each divided body is molded. The first opened
The mold is moved and one of the divided bodies held in the cavity is clamped with respect to the other divided body held in the cavity of the second mold. On the other hand, a resin material injected from the first injection device or the second injection device is fused to form a hollow molded product having a hollow portion therein.

[0009]

As described above, in the conventional multi-layer molding method and hollow molding product molding method, the fixed mold and the movable mold are closed and the divided bodies to be joined are simultaneously formed. After the primary molding step of molding, the mold is opened to move one of the fixed mold or the movable mold in parallel with a mold surface different from the mold clamping direction, and the divided body is moved. It is configured to perform a secondary molding step of positioning at the joining position, closing the mold again, and fusing and joining the divided bodies.

Thus, in the conventional molding method,
In order to move the fixed mold and the movable mold relative to the mold surface, high-precision positioning is required, and in the case of a large molded product, not only a large installation space is required, but also There is a problem in that the weight is increased and the means for moving it is also large, and the equipment cost is significantly increased.

The inventors of the present invention have conducted intensive studies and studies, and as a result, they have provided an intermediate mold between the fixed mold and the movable mold on the fixed mold side and the movable mold side, respectively. After the molten resin is injected into the cavity from the first injection device, the divided bodies of the hollow molded product that can be connected to each other are formed, and then the mold is opened and the intermediate mold is retracted to a predetermined position. The fixed mold and the movable mold are closed as they are, and the divided body of the hollow molded article is joined. The cavity formed around the joint of the divided body of the hollow molded article is melted from the second injection device. Injecting a resin to form a mutually bonded hollow molded article, and in this case, as a means for retracting the intermediate mold, the intermediate mold is detachably held and held as a fixed mold. It is configured to be able to move back and forth between the movable mold and how to open and close the mold. After a fixed mold and a movable mold are closed via an intermediate mold and injection-molded by a first injection device, a certain mold opening space is secured between these molds. By providing an intermediate mold holding mechanism having mold opening means for performing mold opening, it is possible to easily perform positioning between the molds, and to save space and reduce cost even for a large molded product. It has been found that it can be carried out by equipment and that multistage molding of a hollow molded article can be achieved stably and at low cost.

Accordingly, an object of the present invention is to provide a method of molding a hollow molded article in which an intermediate mold is disposed between a fixed mold and a movable mold, and to provide a structure of the intermediate mold and means for holding and moving the same. By improving, it is possible to perform the positioning and movement of each mold easily and smoothly, and to perform the multi-stage molding of the hollow molded product at a low cost with a small space and simple control operation. An object of the present invention is to provide a multi-stage molding method of an article and an injection molding machine for performing the method.

[0013]

In order to achieve the above-mentioned object, a multi-stage molding method of a hollow molded article according to the present invention comprises a step of forming a hollow molded article on a fixed mold side through an intermediate mold between a fixed mold and a movable mold. The molten resin is injected from the first injection device into the cavities provided on the side of the movable mold, respectively, to form mutually divided hollow molded articles, and then the mold is opened to form an intermediate part. After the mold was retracted to a predetermined position, the fixed mold and the movable mold were closed as they were, and the divided parts of the hollow molded article were joined, and formed around the joint of the divided parts of the hollow molded article. It is configured to inject a molten resin from the second injection device into the cavity to form a mutually connected hollow molded product, and when the intermediate mold is retracted, the intermediate mold is detachably held. And make it movable between the fixed mold and the movable mold. Both can be moved in the mold opening / closing direction, and the fixed mold and the movable mold are closed via an intermediate mold, and after a first injection device performs injection molding, a fixed mold is opened between these molds. It is characterized in that the mold is opened so as to secure a space.

Further, as an injection molding machine for carrying out the multi-stage molding method of the hollow molded article, a fixed mold and a movable mold are interposed between a fixed mold and a movable mold via an intermediate mold. A first injection device for injecting a molten resin into a cavity provided in each of the first and second molds to form each of the mutually divided hollow molded articles, and a mold for molding each of the hollow molded articles. After the mold is opened and the intermediate mold is retracted to a predetermined position, the fixed mold and the movable mold are closed as they are, and the divided body of the hollow molded article is joined. A second injection device for injecting a molten resin into a cavity formed around the joint to form a mutually-connected hollow molded product, wherein the intermediate mold is retracted when the intermediate mold is retracted. Can be detachably held and this is fixed mold and moving mold Moving means and a positioning means which can move in the mold opening / closing direction while being able to move forward and backward between the fixed mold and the movable mold. It is characterized in that an intermediate mold holding mechanism provided with a mold opening means capable of securing a constant mold opening space between these molds after injection molding by an injection device is provided.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a multi-stage molding method of a hollow molded article according to the present invention and an injection molding machine for carrying out the method.

FIGS. 1 to 5 show an embodiment of an injection molding machine for carrying out a multi-stage molding method of a hollow molded article according to the present invention. FIG. Plan view, FIG. 2 is an overall plan view in a mold closed state, FIG. 3 is a schematic side view of main parts when a primary injection step is performed in the mold closed state, FIG. 4 is a schematic plan view of main parts in FIG. FIG. 5 is a schematic front view of a main part in a state where the intermediate mold is held by the holding mechanism.

Therefore, the mold used in this embodiment is an intermediate mold 14 between the fixed mold 10 and the movable mold 12.
And a three-piece mold configuration provided with. It should be noted that a normal three-piece mold has a configuration in which the intermediate mold is supported by the dies located on both sides in the mold open state. In the embodiment of the present invention, the intermediate mold is used. 14 is a required mold opening position, from the molds 10 and 12 on both sides,
A structure is adopted in which the support is free.

In FIGS. 1 and 2, a board 18 is placed on a gantry 16 installed on a required floor, and a fixed board 20 is fixedly arranged on the board 18. On the other hand, the moving platen 24 via the tie bars 22
Are arranged opposite to each other so as to be movable forward and backward. The injection nozzles are arranged in a direction parallel to the joining surfaces of the respective dies with respect to the positions of the fixed dies 10, the movable dies 12, and the intermediate dies 14, which are attached to the fixed plate 20 and the movable plate 24, respectively. A first injection device 26 oriented at the portion 26a is provided, and a second injection device 28 oriented at an injection nozzle portion 28a is provided at the center of the mold surface of the fixed mold 10.
Reference numeral 30 denotes a mold opening / closing driving device for moving the moving board 24 along the tie bar 22.

However, in the injection molding machine of the present embodiment, as shown in FIG. 3, a pit 32 having a required depth is excavated and set on the floor on which the gantry 16 is installed. The intermediate mold 14 is configured so that the intermediate mold 14 can be engaged and disengaged so that the intermediate mold 14 can move forward and backward between the fixed mold 10 and the movable mold 12 and can also move in the mold opening and closing direction. The mold holding mechanism 34 is housed and arranged.

In FIG. 3, this intermediate mold holding mechanism 34
Includes a fixed support member 36 and a movable support member 38 coupled to the fixed support member 36 so as to be movable (movable in the vertical direction in the illustrated example), and a support rod 38a of the movable support member 38 An intermediate mold holder 40 that holds the intermediate mold 14 in a freely detachable manner is coupled thereto (see FIG. 5). The support rod 38a of the movable support member 38 has a piston rod 42a, a piston rod 42a, a movable rod 24, and a fixed plate 20 that supports the movable mold 12, respectively.
A metal which can abut one end of 2b to secure a fixed mold opening space in which the intermediate mold 14 can move forward and backward from the fixed mold 10 and the movable mold 12 when the mold is opened. A mold opening cylinder 42 is provided.

Further, in FIG. 3, the movable support member 38 is configured to be movable forward and backward with respect to the fixed support member 36 by a movable cylinder 44 as a forward and backward moving means, and the fixed support member 36 is slid in the pit 32. It is placed on a moving member 46 and is configured and arranged to be movable in a mold opening and closing direction by a pair of positioning cylinders 48, 48 as position adjusting means.

Therefore, in the present embodiment, the intermediate mold 14
As shown in FIG. 5, the intermediate mold 14 is moved between the fixed mold 10 and the movable mold 12, and the opening and closing movement of these molds is performed smoothly and reliably. And a pair of key grooves 50a, 50 provided on the bottom of the
a and keys 52a, 52a to be fitted thereto, both sides of the intermediate mold 14, and the corresponding intermediate mold holder 4
A pair of key grooves 50b respectively provided in the mold housing portions
With the key 50b and the keys 52b, 52b fitted to the key 50b, it is possible to easily perform appropriate positioning at the time of attaching / detaching the intermediate die 14 to / from the intermediate die holder 40. Note that a pair of key grooves 50a, 50a and keys 52a, 52a
Alternatively, the mounting can be performed with a pin hole and a pin, or the mounting relationship between them can be reversed.

In opening and closing operations of the respective dies,
Guide holes 54a and 56a are bored by being displaced on both side surfaces of the intermediate mold 14, and guide pins 54b are protrudingly provided on the opposing surface of the fixed mold 10 corresponding to the intermediate mold 14, and the movable mold is provided. A guide pin 56b protrudes from the opposing surface of the twelve. The movable mold 12 has a guide hole 54c and a fixed mold 1 corresponding to the guide pin 54b of the fixed mold 10 and the guide pin 56b of the movable mold 12, respectively.
A guide hole 56c is drilled in the hole 0 (see FIG. 1). Therefore,
Guide pins 54 provided on these dies 10, 12, 14
b, 56b and corresponding guide holes 54a, 56a
And 54c, 56c, the opening and closing operation of the dies can be performed appropriately and easily.

The fixed mold 10 and the movable mold 12
Are detachably attached to the fixed platen 20 and the moving platen 24 via a known mold automatic clamping device (not shown).

Next, a multi-stage molding method of a hollow molded article by the injection molding machine having the above-described configuration will be described with reference to FIGS. 3, 4, and 6 to 9.

(1)Mold closing process by primary injection molding
[See Step (1) in FIGS. 3, 4 and 9] First, as shown in FIG.
12 is held in the intermediate mold holder 42 in the mold open state
The fixed intermediate mold 14 and the movable mold 12
During this time, the moving cylinder 44 of the intermediate mold holding mechanism 34 is moved.
To move up to a predetermined position.

Next, as shown in FIGS. 3 and 4, the movable mold 12 is moved by the mold opening / closing drive device 30, the mold is closed to the fixed mold 10 via the intermediate mold 14, and the mold is closed. The first injection device 26 performs injection filling of the molten resin into each mold cavity, that is, primary injection molding. In this primary injection molding, the first injection device 2
The molten resin injected from 6 is filled into the mold cavities formed in the left and right stationary dies 10 and the movable dies 12 via the intermediate dies 14.

(2) Mold Opening Step After Primary Injection Molding [See Step (2) in FIGS. 6 and 9] When the primary injection molding by the first injection device 26 is completed, first, an intermediate mold holding mechanism 34 mold opening cylinder 42
To move the stationary mold 10 and the movable mold 12 opposite to the intermediate mold 14 simultaneously or sequentially via the piston rods 42a and 42b (see FIG. 6A). As a result, in the mold cavities of the fixed mold 10 and the movable mold 12, for example, divided bodies S 1 and S 2 of a hollow molded article as shown in FIG. Splits S1 and S from intermediate mold 14
It is preferable that the release of the mold 2 starts the releasing operation at the same time so as not to affect the quality of the final molded product. Also,
The space between the intermediate mold 14, the fixed mold 10, and the movable mold 12 is the minimum space in which the intermediate mold 14 can move forward and backward.

(3)Mold closing process by secondary injection molding
[See step (3) in FIGS. 7 and 9] As described above, the first injection device 26 allows the fixed mold 10
And the moving mold 12 are hollow in the mold cavities, respectively.
When the divided bodies S1 and S2 of the molded article are molded, FIG.
As shown in FIG.
The intermediate mold 14 is moved to the moving mold of the intermediate mold holding mechanism 34.
By operating the slider 44, it is moved down to a predetermined position.
Next, the positioning cylinders 48, 48 are operated to
For closing the intermediate mold 14 between the fixed mold 10 and the movable mold 12
Position it so that it does not buffer. And mold opening and closing
The movable mold 12 is moved by the driving device 30 to
Close the mold to the mold 10 and perform the second injection in the clamped state.
With the device 28, the fixed mold 10 and the movable mold 12
The formed mold cavity C1 (see FIG. 7B)
On the other hand, injection filling of molten resin, that is, secondary injection molding is performed.
U.

(4) Mold Opening Step After Secondary Injection Molding [See Step (4) in FIGS. 8 and 9] When the second injection molding by the second injection device 28 is completed, the mold moves with the fixed mold 10. As shown in FIG. 8B, the hollow molded product formed by the mold 12 is such that the divided bodies S1 and S2 are connected to each other by the bonding resin S3 to form a single hollow molded product 60. . Therefore, the hollow molded product 60 can be taken out by operating the mold opening / closing drive device to separate the movable mold 12 from the fixed mold 10 and open the mold.

FIG. 9 shows a time chart of the operation of each operating member in the multi-stage molding method of the hollow molded article by the injection molding machine described above. here,
B indicates retreat / metering, F indicates forward / eject, U indicates ascending, and D indicates a descending state.

Although the preferred embodiments of the present invention have been described in various ways, the present invention is not limited to the case where the intermediate mold is moved up and down as in the above-described embodiments. It is also possible to implement the configuration for moving in the forward and backward directions by a similar device configuration, and many other design changes are possible without departing from the spirit of the present invention.

[0033]

As described above, the multi-stage molding method for a hollow molded article according to the present invention is directed to the fixed mold side and the movable mold side via the intermediate mold between the fixed mold and the movable mold. Inject molten resin from the first injection device into the cavity provided respectively,
After forming the divided bodies of the hollow molded article that can be connected to each other, and then opening the mold and retracting the intermediate mold to a predetermined position, the fixed mold and the movable mold are closed as they are. The divided bodies of the hollow molded article are joined together, and a hollow molded article is formed by injecting a molten resin from a second injection device into a cavity formed around a joint portion of the divided body of the hollow molded article and joining each other. When the intermediate mold is retracted, the intermediate mold is removably held, and the intermediate mold is removably held between a fixed mold and a movable mold. After a fixed mold and a movable mold are closed via an intermediate mold and injection-molded by a first injection device, a certain mold opening space is secured between these molds. By configuring the mold to open to obtain the mold phase In addition to being able to easily perform positioning, large-sized molded products can be implemented with low-cost equipment by saving space, and multistage molding of hollow molded products can be achieved stably and at low cost. it can.

Therefore, as an injection molding machine for multi-stage molding of the hollow molded article according to the present invention, the fixed mold and the movable mold are interposed between the fixed mold and the movable mold via an intermediate mold. A first injection device for injecting a molten resin into a cavity provided in each of the first and second molds to form each of the mutually divided hollow molded articles, and a mold for molding each of the hollow molded articles. After the mold is opened and the intermediate mold is retracted to a predetermined position, the fixed mold and the movable mold are closed as they are, and the divided body of the hollow molded article is joined. For injecting a molten resin into a cavity formed around the part to form a mutually connected hollow molded article
When the intermediate mold is retracted, the intermediate mold is removably held, and the intermediate mold is removably held between a fixed mold and a movable mold, and the mold is opened and closed. Moving means and positioning means for allowing movement in the direction, and further, a fixed mold and a movable mold are closed via an intermediate mold, and after injection molding by a first injection device, these molds are interposed. By providing an intermediate mold holding mechanism with a mold opening means that can secure a fixed mold opening space, multistage molding of hollow molded products can be achieved stably and at low cost with a relatively simple structure. can do.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing a main part of an embodiment of an injection molding machine for carrying out a multistage molding method of a hollow molded product according to the present invention.

FIG. 2 is a schematic plan view showing the entire injection molding machine in a state where a mold is closed in the injection molding machine shown in FIG.

FIG. 3 is a view showing a state where the mold is closed in the injection molding machine shown in FIG.
It is a principal part schematic side view which shows the state which performs a next injection process.

4 is a schematic plan view of a main part of the injection molding machine shown in FIG.

5 is a schematic front view of a main part of the injection molding machine shown in FIG. 3, showing a state in which an intermediate mold is held by a holding mechanism.

6 (a) is a schematic side view showing a main part of the injection molding machine shown in FIG. 3 after a primary injection step is completed and a mold is opened, and FIG. FIG. 4 is a cross-sectional view of a hollow molded product.

FIG. 7 (a) shows a state in which the intermediate mold is retracted and the fixed mold and the movable mold are closed in the injection molding machine shown in FIG.
It is a principal part schematic side view which shows the state which performs a next injection process, (b) is sectional drawing which shows the state which joined the hollow molded article shape | molded by the primary injection process.

FIG. 8A is a schematic side view of a main part showing a state in which a fixed mold and a movable mold are opened to take out a hollow molded product in the injection molding machine shown in FIG. 7, and FIG. It is sectional drawing which shows the completed state of the hollow molded article shape | molded by the injection process.

FIG. 9 is a time chart showing an operation state of a molding step for performing the multi-stage molding method of the hollow molded article according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 fixed mold 12 movable mold 14 intermediate mold 16 gantry 18 substrate 20 fixed board 22 tie bar 24 movable board 26 first injection device 26a injection nozzle unit 28 second injection device 28a injection nozzle unit 30 mold opening / closing drive device 32 Pit 34 Intermediate mold holding mechanism 36 Fixed support member 38 Moving support member 38a Support rod 40 Intermediate mold holder 42 Mold opening cylinder 42a, 42b Piston rod 44 Moving cylinder (advancing and retreating means) 46 Sliding member 48 Positioning cylinder (position) Adjusting means) 50a, 50b Key groove 52a, 52b Key 54a, 56a Guide hole 54b, 56b Guide pin 54c, 56c Guide hole 60 Hollow molded product

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI // B29L 22:00

Claims (2)

[Claims] 1. A molten resin is injected from a first injection device into cavities provided on a fixed mold side and a movable mold side via an intermediate mold between a fixed mold and a movable mold, respectively. After forming the divided bodies of the hollow molded article that can be connected to each other, and then opening the mold and retracting the intermediate mold to a predetermined position, the fixed mold and the movable mold are closed as they are. The divided bodies of the hollow molded article are joined together, and a hollow molded article is formed by injecting a molten resin from a second injection device into a cavity formed around a joint portion of the divided body of the hollow molded article and joining each other. When the intermediate mold is retracted, the intermediate mold is removably held, and the intermediate mold is removably held between a fixed mold and a movable mold. To the fixed mold and the movable mold via the intermediate mold. A multi-stage molding method for a hollow molded article, wherein a mold is opened so that a certain mold opening space can be secured between these molds after the mold is closed and injection molded by a first injection device. . 2. Hollows capable of mutually injecting molten resin into cavities provided on the fixed mold side and the movable mold side via an intermediate mold between the fixed mold and the movable mold, respectively. A first injection device for molding each of the divided bodies of the molded article, and a mold in which each of the divided bodies of the hollow molded article is molded is opened to retract the intermediate mold to a predetermined position. The mold and the movable mold are closed as they are, and the divided body of the hollow molded article is joined, and the molten resin is injected into the cavity formed around the joint of the divided body of the hollow molded article, and the hollow parts are connected to each other. And a second injection device for molding a molded product. When the intermediate mold is retracted, the intermediate mold is detachably held and held between a fixed mold and a movable mold. A moving means and a moving means that can move in the mold opening and closing direction And a positioning means, and a mold capable of securing a fixed space between the molds after the fixed mold and the movable mold are closed via a middle mold and injection-molded by the first injection device. An injection molding machine for forming a hollow molded product in multiple stages, comprising an intermediate mold holding mechanism having an opening means.