JPH1110675A - Molding method of molding and molding die - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of molding molded form, capable of molding a thick molded form with a high accuracy. SOLUTION: A molding method employs a stationary mold 1, a movable mold 10, clamped and released with respect to the stationary mold 1, and cores 20, 20 while cavities 2, 2 are blocked by the cores 20, 20 and molten resin is injected into another cavity 11 to effect the primary molding of a part of a molded form. Subsequently, the cores 20, 20 are removed and molten resin is injected into the cavities 2, 2, produced by removing the cores 20, 20, to obtain the molded form by integrating the remaining part of the molded form with another part obtained by the last injection.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention is not limited to the use of a fixed mold, a movable mold that is clamped and opened with respect to the fixed mold, and a core. The present invention relates to a molding method for molding a molded article having a large difference in thickness, and a molding die used for performing the molding method.

[0002]

2. Description of the Related Art Injection molding machines are well known, not to mention the name of the literature.
It comprises a movable mold to be opened, a mold clamping device for clamping these molds, an injection unit for measuring and injecting a resin material. Therefore, when the resin material is measured by the injection unit and the measured molten resin material is injected into the cavity of the clamped mold, a molded product having a predetermined shape can be obtained.

[0003]

As described above, a molded article having a general shape can be molded by using a conventionally known injection molding machine or a mold and by a conventionally known method. However, if a part of the molded product has a thick portion or a complicated shape, a problem may occur. For example,
As shown in FIG. 3A, a molded product including a plate-like portion D having a substantially uniform thickness and two prismatic legs K, K has thick portions N, N. Since there is such a thick part N, when obtaining a molded product having a thick part N, the "thickness" of the thick part,
"Voids" and the like become large, and the accuracy, quality and the like of the molded product may be reduced. To explain in more detail, the filled resin material in a molten state is cooled,
The transition from the molten state to the solid state occurs, and with this transition, the specific volume (density) changes. This change is also affected by the cooling state, but correlates with the thickness of the molded product, and sinks, voids, etc. of the thickened portion become large, and the accuracy, quality, etc. of the molded product having the thickened portion generally decrease. Will be. Furthermore, in order to open the movable mold and take out the molded product, it is necessary to wait for the cooling and solidification of the injected molten resin, but since the cooling and solidification time increases rapidly in proportion to the thickness of the molded product, These thick portions N, N increase the molding cycle. Such a problem of the quality of the molded product, the problem of the molding cycle, and the like can be solved to some extent by designing the molded product so that the molded product does not have a thick portion. However, another problem arises in that the shape of the molded product is restricted. In addition, the conventional molding method has a disadvantage that an injection unit with a large capacity is required to obtain a molded product with a large capacity, and a molded product with a large capacity cannot be molded at low cost. The present invention seeks to provide a molding method and a molding die that solve the above-mentioned conventional problems, and specifically, a molding method capable of molding a molded product having a thick portion with high precision. It is an object of the present invention to provide a method for molding an article and a molding die used for carrying out the method. Further, it is also possible to provide a molding method and a molding die for a molded article having a high degree of freedom in the shape design of the molded article. It is another object to provide a molding method and a molding die.

[0004]

The above objects of the present invention can be attained by forming a molded article into parts. That is, the present invention, in order to achieve the above object, a fixed mold, a mold clamped to the fixed mold, a movable mold to be opened,
Using a core, a part of the cavity is closed by the core, a molten resin is injected into an unblocked part to form a part of a molded product, and then the core is pulled out and the part is pulled out. The other part of the molded article is then integrated with the previously obtained part by injection of molten resin to obtain a molded article. The invention according to claim 2 is such that a part of the molded article according to claim 1 is obtained by primary molding and the other part is obtained by secondary molding, and the invention according to claim 3 Is configured such that a part of the molded product obtained by the first injection according to claim 1 or 2 is a uniform thick portion. The invention according to claim 4 includes a fixed mold, a movable mold that is clamped and opened with respect to the fixed mold, and a core, wherein the fixed mold and the movable mold include: A cavity having a predetermined shape for obtaining a molded product is formed, and the core is provided so as to be freely inserted into and removed from the cavity. According to a fifth aspect of the present invention, the cavity of the fourth aspect is
When the core is inserted, the remaining cavity portion is configured to be a space having a uniform thickness.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to FIG. 3A, in which a plate-like portion D having a substantially uniform thickness and two prismatic legs K, K are shown. As shown in FIG. 3 (b), a molded product consisting of
An example will be described in which the plate-shaped portion D is formed by primary forming and the legs K, K are formed by secondary forming separately into the individual legs K, K. FIG. 1A is a schematic cross-sectional view of a mold according to the present embodiment, and FIG. 1B is a cross-sectional view of FIG. FIG. 1A is a cross-sectional view as viewed in the direction of the arrow harha in FIG. 1A, and FIG. 1D is an enlarged perspective view of the runner switching unit. As shown in FIG. 1, a mold according to the present embodiment includes a fixed mold 1 fixed to a fixed platen and a mold clamped or driven in the mold opening direction with respect to the fixed mold 1. And a core 20, 20 as described later in detail.

[0006] In the fixed mold 1, two second cavities 2, 2 for molding the legs K, K are formed so as to open to the parting surface. The stationary mold 1 is provided with a sprue bush to which an injection nozzle is touched during injection, a sprue 3 through which molten resin flows, and the like.

The movable mold 10 is provided with a first cavity 11 for forming the plate-shaped portion D. The first cavity 11 is open on the parting surface and corresponds to the second cavities 2 and 2 of the fixed mold 1. According to the present embodiment, the depth of the first cavity 11 is constant. Therefore, the molded product obtained by the first cavity 11 has a uniform thickness, and a highly accurate plate-shaped portion D is molded. As shown in FIGS. 1 (b) and (c), three runners 12, 4, and 4 are provided on the parting surface of the movable mold 10 at positions that do not interfere with each other. One of these runners 12, 4, 4
The other of the runners 12 communicates with one sprue 3 provided on the fixed mold 1, the other of the runners 12 is connected to the first cavity 11 of the movable mold 10 via a gate (not shown), and the other of the runners 4, 4 is Similarly, they communicate with the second cavities 2 and 2 of the fixed mold 1 via respective gates (not shown).

The sprue 3 is connected to the runner 12 as described above.
, And also to the runners 4, 4, a runner switching device 5 for switching between them is provided. The runner switching device 5 includes a spool 6. As shown in the enlarged view of FIG. 1D, three concave grooves 4 ', 4', 12 'are formed on the spool 6 at predetermined intervals. These three grooves 4 ', 4', 12 'are all open to the parting surface. Therefore, when the movable mold 10 is opened,
The sprue runner can be easily taken out. The spool 6 configured as described above includes the runner 12,
The movable mold 10 is provided across the movable mold 4 and 4 and is driven in the axial direction by the runner switching cylinder unit 7. When the spool 6 is driven to the first position by the runner switching cylinder unit 7, the concave groove 12 'of the spool 6 is aligned with the runner 12, as shown in FIG. When driven to the position, the concave grooves 4 ', 4' of the spool 6 are now aligned with the runners 4, 4, as shown in FIG.

The cores 20, 20 are formed in a size corresponding to the size and length of the second cavities 2, 2 of the fixed mold 1, and the core switching cylinder units 21, 2
1 drives the cavities 2 and 2 in the vertical direction in FIG. That is, when the cores 20, 20 are inserted into the second cavities 2, 2 of the fixed mold 1, the second cavities 2, 2 are closed, and the plate-like portion D is formed by the first cavity 11 of the movable mold 10. Can be formed, and when it is removed, the legs K, K can be formed by the second cavities 2 and 2.

Next, a molding method using the above mold will be described. The cores 20, 20 are driven downward by the core switching cylinder units 21, 21 to close the second cavities 2, 2 of the fixed mold 1. Further, the spool 6 is driven to the first position by the runner switching cylinder unit 7.
Then, the mold is clamped. Then, the first of the movable mold 10
Only the cavity 11 can be filled. This state is shown in FIG. 2A with the resin material partially filled. Inject the separately measured molten resin. The molten resin is supplied to the sprue 3 and the groove 1 of the runner switching device 5
2 ', the first cavity 11 is filled through the runner 12 and the gate. The plate-shaped portion D is formed by this primary forming.

After cooling and solidification, the movable mold 10 is cut off by the sprue runner SR and opened at intervals necessary for the movement of the cores 20, 20 and the like. The plate-shaped portion D is a movable mold 10
Is opened, and in the case of a side gate, a sprue runner SR is cut off because a gate cut is provided although not shown in the figure. This state is shown in FIG. The cores 20, 20 are driven upward by the core switching cylinder units 21, 21 to open the second cavities 2, 2 of the fixed mold 1, as shown in FIG. I do. The spool 6 is driven to the second position by the runner switching cylinder unit 7. Then, the mold is clamped. Then, fixed mold 1
Only the second cavities 2 and 2 can be filled. The mold is clamped, and the newly measured molten resin or the molten resin left in the primary molding is injected. The molten resin is filled into the second cavities 2 and 2 through the sprue 3, the concave grooves 4 'and 4', the runners 4 and 4, and the gate. The state of the injection is shown in FIG. By this secondary forming, the legs K, K are formed into the previously formed plate-like portion D.
And molded. After cooling and solidification, the movable mold 10 is opened, and the molded product is taken out by the ejector device. Hereinafter, molding is performed in the same manner.

The present invention can be implemented in various forms without being limited to the above embodiment. For example, in the above embodiment, two core switching cylinder units 21, 21 are provided for two cores 20, 20, but the number of cores, the number of core switching cylinder units, and the like are different. It is apparent that the present invention can be implemented without being limited to the embodiment. Further, in the above embodiment, the molded article is divided into two parts and molded. However, when the molded article has a large thickness or is complicated in shape, a plurality of cores are used. It is also apparent that the molding can be performed in a similar manner from a plurality of portions by the third molding or higher molding. Further, although the structure becomes complicated, it is apparent that the cores 20 and 20 can be provided and provided in the movable mold 10.

[0013]

As described above, according to the present invention, a fixed mold, a movable mold that is clamped and opened with respect to the fixed mold, and a core are used, and the cavity is formed by the core. Part of the molded product, and inject the molten resin into the unblocked part to form a part of the molded product. Since the molded part is integrated with the part obtained by previously injecting the part, a molded part with a thick part can be obtained with high precision and high quality without sink marks and voids. The effect unique to the present invention is obtained. Further, according to the present invention, since the molded product is formed by dividing the molded product into parts, the degree of freedom in the shape of the molded product is large, and a complicated molded product can be molded. Is also obtained. Furthermore, since the molded product is divided into parts and molded, while the previously filled molten resin is solidified, the resin material for molding other parts can be measured, and the capacity is larger than the capacity of the injection unit. Molded articles can also be obtained. That is, a large-capacity molded product can be molded by a small injection molding machine. In addition, since the molded article is divided into parts and molded, there is no thick part, and the cooling and solidifying time is shortened. Therefore, the molding cycle can be shortened as a whole, despite the fact that the molding is divided into parts. According to another invention, since a part of a molded product obtained by first injection is a uniform thickness portion, a part requiring injection accuracy is molded first, and a high-precision molded product is formed. Is obtained.

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of the present invention. FIG. 1A is a schematic cross-sectional view of a mold, and FIG. 1B is a cross-sectional view of FIG. FIG. 1C is a cross-sectional view of FIG. 1A taken in the direction of the arrow harha, and FIG. 2D is an enlarged perspective view of a spool of the runner switching unit.

FIG. 2 is a view showing each state of molding using a mold according to an embodiment of the present invention, in which (a) performs primary molding and (b) performs secondary molding. FIG.

FIG. 3 is a view showing an example of a molded product, in which (a) is a perspective view of the entirety, and (b) is a front view, which is divided into two parts.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixed die 2, 2 Second cavity 4, 4 Runner 5 Runner switching device 7 Runner switching cylinder unit 10 Movable die 11 First cavity 12 Runner 20, 20 Core 21, 21 Core switching cylinder unit

Claims (5)

[Claims] 1. A fixed mold (1), a movable mold (10) which is clamped and opened with respect to the fixed mold (1), and a core (2).
0, 20), and a part of the cavities (2, 2, 11) is closed by the cores (20, 20), and the molten resin is injected into the unblocked part (11) and molded. A part (D) of the product is molded, and then the cores (20, 20) are removed, and the molten resin is injected into the removed portions (2, 2) to form the remaining other portions (K, K) of the molded product Is molded with the part (D) obtained by previously injecting to obtain a molded product. 2. A part (D) of the molded article according to claim 1.
But by primary forming and the remaining other parts (K, K)
Is obtained by secondary molding. 3. A method for molding a molded article according to claim 1, wherein a part (D) of the molded article obtained by injection in advance is a uniform thick part. 4. A fixed mold (1), a movable mold (10) clamped and opened with respect to the fixed mold (1), and a core (2).
0, 20). The fixed mold (1) and the movable mold (10) are provided with cavities (2, 2, 11) of a predetermined shape for obtaining a molded product, and the core ( 20) and 20) are provided so as to be freely inserted into and removed from the cavities (2, 2, 11). 5. The cavity (2, 2,...) According to claim 4,
11) A mold for molding a molded product, in which the cavity portion (11) which remains when the cores (20, 20) are inserted becomes a space having a uniform thickness.