JP4081201B2 - Tandem injection molding apparatus and method of manufacturing molded product using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tandem injection molding apparatus and a method of manufacturing a molded product using the same, and more specifically, in the case of manufacturing two molded products simultaneously by supplying molten metal to two cavities having different volumes. A tandem mold capable of producing a molded product without producing a defective portion in one of the cavities having a large volume, and capable of obtaining a molded product in which no burr portion is formed in the other cavities having a small volume. The present invention relates to an injection molding apparatus and a method of manufacturing a molded product using the same.
[0002]
[Prior art]
An example of a schematic configuration of a conventional tandem injection molding apparatus is shown in FIG. In the tandem injection molding apparatus 1, a fixed platen 2 is disposed on the left side, and a movable platen 3 is disposed on the right side. The movable platen 3 can be moved toward or away from the fixed platen 2 by moving the first cylinder rod 5 in the first cylinder 4 back and forth. The fixed platen 2 and the movable platen 3 are connected by four tie bars 6 at each corner. In FIG. 5, two of the four tie bars 6 are shown.
[0003]
In this case, a first mold 7 that is a fixed platen side mold is installed on one side of the fixed platen 2, and a second mold that is a movable platen side mold is installed on one side of the movable platen 3. 8 is installed. A third mold 9 (hereinafter also referred to as a central mold 9) is disposed between the first mold 7 and the second mold 8. That is, three molds 7, 8 and 9 are arranged along the longitudinal direction of the tandem injection molding apparatus 1. The central mold 9 is cantilevered by the second cylinder 10 on the second mold 8 side, and the second cylinder rod 11 in the second cylinder 10 moves forward and backward to move the second mold. 8 can be approached or separated.
[0004]
Further, an injection mechanism 12 for injecting molten resin or the like (molten metal) is installed on the other side of the fixed platen 2, and the first mold 7 and the central mold 9 are respectively injected with the injected Passages 14a and 14b, which are paths when the molten metal is introduced into two cavities 13a and 13b described later, are formed.
[0005]
For example, when an injection molded product made of a resin material is manufactured by the tandem injection molding apparatus 1 having such a configuration, first, the movable platen 3 is driven so as to approach the fixed platen 2, and the first mold is driven. 7 and the central mold 9 are brought into close contact with each other, and the central mold 9 and the second mold 8 are brought into close contact with each other.
[0006]
FIG. 6 shows a schematic vertical cross section in a state where the three molds 7, 8, and 9 are in close contact with each other. As shown in FIG. 6, when these molds 7, 8, 9 are brought into close contact with each other, a relatively large capacity cavity 13 a is formed by the first mold 7 and the central mold 9, and the central mold is formed. The mold 9 and the second mold 8 form a cavity 13b having a smaller volume than the cavity 13a.
[0007]
Next, molten metal L made of synthetic resin is injected from the injection mechanism 12, and the molten metal L is introduced and filled into the cavities 13a and 13b through the passages 14a and 14b, respectively. After a predetermined time has elapsed, the molten metal L is solidified and formed into a shape corresponding to the shape of the cavities 13a and 13b.
[0008]
After solidifying and molding the molten metal L, the first mold 7 and the central mold 9 and the central mold 9 and the second mold 8 are separated by moving the movable plate 3 away from the fixed platen 2. The molded product P1 is obtained from the cavity 13a, and the molded product P2 is obtained from the cavity 13b.
[0009]
[Problems to be solved by the invention]
By the way, when manufacturing a molded product in the injection molding apparatus 1 having the above-described configuration, there is a problem that the obtained molded products P1 and P2 do not have a desired shape and the manufacturing quality is not constant.
[0010]
That is, a part of the molded product P1 manufactured with the cavity 13a having a large volume may be missing for the reason described below.
[0011]
When the molten metal L starts to be introduced into the cavities 13a and 13b at the same time, the cavities 13b having a small volume are filled first as shown in FIG. Since the cavity 13a is not yet sufficiently filled with the molten metal L at this time, the molten metal L is continuously injected from the injection mechanism 12 and supplied to the cavity 13a. However, even if the molten metal L is supplied in this way, a part of the molten metal L already introduced into the cavity 13a starts to solidify, and therefore the newly injected molten metal L is not sufficiently introduced into the cavity 13a. As a result, the amount of the molten metal L introduced into the cavity 13a may be insufficient. When the molten metal L is solidified with an insufficient amount of the molten metal L introduced, the molded product P1 is partially missing as shown by the broken line in FIG.
[0012]
On the other hand, as shown in FIG. 5, the burr | flash part P2a may be formed in the molded article P2 manufactured with the cavity 13b with small volume. That is, as described above, even after the cavity 13b is filled with the molten metal L, the injection of the molten metal L is continued in order to fill the cavity 13a. For this reason, the molten metal L is excessively supplied to the cavity 13b. There is. As a result, the central mold 9 and the second mold 8 are pressed by the excessively supplied molten metal L, and the adhesion between the central mold 9 and the second mold 8 is lowered as shown in FIG. A gap 15 is generated. When the melt L supplied excessively enters the gap 15 and solidifies, it becomes a burr portion P2a.
[0013]
As described above, when trying to simultaneously manufacture molded products having different volumes, it is not only possible to obtain a molded product having a desired molding quality, but also results in an increase in product price and a decrease in production efficiency. There is an inconvenience. That is, the yield of the molded product is not good, and when a burr portion is formed on the molded product, a deburring process or the like for removing it is necessary.
[0014]
The present invention has been made to solve the above-described problems, and in a tandem injection molding apparatus, a molded product obtained from a cavity with a large volume and a molded product obtained from a cavity with a small volume both have a desired shape and a desired quality. It is an object to provide a tandem injection molding apparatus and a molding method for a molded product using the same, which can secure a high yield of molded products and can improve the production efficiency of molded products. And
[0015]
[Means for Solving the Problems]
In order to achieve the above object, a tandem injection molding apparatus according to the present invention includes a stationary platen,
A fixed platen mold installed on one side of the fixed plate;
A movable plate connected to the fixed plate so as to approach or separate from the fixed plate;
A movable platen mold installed on one side of the movable plate;
A central mold interposed between the fixed platen mold and the movable platen mold, and in close contact with the fixed platen mold and the movable platen mold when manufacturing a molded product;
An injection mechanism for injecting molten metal installed on the other side of either the fixed platen or the movable platen;
A first passage that is formed in one of the fixed platen mold or the movable platen mold in which the injection mechanism is installed and through which the molten metal passes;
A second passage communicating with the first passage formed in the central mold ;
Comprising
At the time of manufacturing a molded product, either the fixed platen mold or the movable platen mold in which the first passage is formed and the central mold are brought into close contact with each other so that the first cavity is the first cavity. together are formed in communication with the passage, the remaining one and a central mold and the adhesion has been the first small second volume than cavity the stationary platen side mold or the movable platen side mold A cavity is formed in communication with the second passage ;
At the entrance of the second passage formed in the central mold, the introduction of the melt into the second passage and the second cavity is stopped or closed by closing or opening the second passage. An opening / closing mechanism for starting is provided.
[0016]
By configuring the tandem injection molding apparatus as described above, a predetermined amount of molten metal is first introduced into the first cavity, and then the release mechanism is energized to open the second passage to the second cavity. The molten metal is simultaneously introduced into the remaining space in the first cavity and the second cavity. Thereby, the molten metal can be supplied into the first and second cavities under the same conditions.
[0017]
In this case, if the opening / closing mechanism is composed of a cylinder installed in the central mold and an opening portion of the second passage through which the cylinder rod of the cylinder is fitted or detached, the cylinder can be easily moved forward and backward. The second passage can be closed or opened.
[0018]
When the cylinder is thus installed in the central mold, the second mold is formed on either the fixed platen mold or the movable platen mold that forms the second cavity together with the central mold. When the cavity is formed, a space for accommodating the cylinder may be provided. This is because the injection molding apparatus is not increased in size and a reliable opening / closing operation of the mold can be obtained.
[0019]
The cylinder rod may be inserted through the center of the second passage. As a result, the tip of the cylinder rod is reliably fitted or detached from the second passage, so that the second passage can be opened and closed reliably.
[0020]
Further, the present invention is a method for manufacturing a molded product that uses the tandem injection molding apparatus configured as described above to manufacture a molded product, wherein the second passage is closed and only the first cavity is Introducing the molten metal through the first passage; opening the second passage; and passing the first passage and the second cavity into the remaining space in the first cavity and the second cavity. And a step of simultaneously introducing the molten metal through the two passages.
[0021]
In this case, it is preferable that the opening of the second passage is performed when the volume of the remaining space of the first cavity and the volume of the second cavity become the same.
[0022]
By introducing the molten metal in this manner, the filling of the molten metal in the first and second cavities is completed substantially simultaneously. Therefore, a defect part does not arise in the molded product manufactured by the first cavity, and a burr part does not form in the molded product manufactured by the second cavity. As a result, the yield of molded products is improved and the production efficiency is improved.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the tandem injection molding apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. Components corresponding to those shown in FIGS. 5 and 6 are given the same reference numerals, and detailed description thereof is omitted.
[0024]
FIG. 1 shows an outline of a tandem injection molding apparatus 20 according to the present embodiment. In the tandem injection molding apparatus 20, the fixed platen 2 is arranged on the left side, and the movable platen 3 is arranged on the right side. The movable platen 3 can be moved toward or away from the fixed platen 2 by moving the first cylinder rod 5 of the first cylinder 4 back and forth. The fixed platen 2 and the movable platen 3 are connected by four tie bars 6 at each corner.
[0025]
A first mold 7 is installed on one side of the fixed platen 2, and a second mold 8 is installed on one side of the movable platen 3. The second mold 10 is cantilevered between the first mold 7 and the second mold 8 by the second cylinder 10, and the second cylinder 10 includes the second mold 10. A central mold 9 that can be moved closer to or away from the second mold 8 by moving the cylinder rod 11 forward and backward is disposed. Further, the first mold 7 and the central mold 9 are respectively formed with passages 14a and 14b for introducing the molten metal into the cavity.
[0026]
Further, a hydraulic cylinder 22 is installed in the central mold 9, and the hydraulic cylinder 22 is attached to the second mold 8 when the second mold 8 and the central mold 9 are brought into close contact with each other. A space portion 24 for accommodating is formed. That is, when these molds 7, 8, 9 are brought into close contact with each other, the hydraulic cylinder 22 is accommodated in the space portion 24, so that the entire tandem injection molding apparatus 20 needs to be enlarged by providing the hydraulic cylinder 22. There is no. Here, the first mold 7, the central mold 9, and the second mold 8 are brought into close contact with each other, and the cavity 13 a is formed by the first mold 7 and the central mold 9, and the central mold 9 and the second mold 8 are formed. FIG. 2 shows a schematic longitudinal section in a state where a cavity 13b having a volume smaller than that of the cavity 13a is formed by 8.
[0027]
In this case, as shown in FIG. 2, the passage 14 b is bent, and one end (opening) 28 faces the exit portion of the passage 14 a of the first mold 7, and the diameter is once increased in a tapered shape. After that, it rises slightly downstream from the central portion, extends in the horizontal direction at the end portion, expands into a nozzle shape, and communicates with the cavity 13b.
[0028]
A cylinder rod 26 of the hydraulic cylinder 22 is inserted through the center of the passage 14b. The diameter of the tip of the cylinder rod 26 is equal to the diameter of the opening portion 28 of the passage 14b. When the cylinder rod 26 is extended to the maximum with respect to the first mold 7, as shown in FIG. The tip of the cylinder rod 26 is fitted into the opening 28 of the passage 14b. That is, the communication of the passage 14b with the cavity 13b is blocked.
[0029]
Therefore, when the molten metal L is injected from the injection mechanism 12 in this state, the molten metal L is introduced into the cavity 13a through the passage 14a, but not introduced into the cavity 13b (see FIG. 2).
[0030]
On the other hand, when the cylinder rod 26 is retracted, the cylinder rod 26 is detached from the opening 28. That is, the passage 14b is opened, and the introduction of the molten metal L into the cavity 13b is started as will be described later.
[0031]
That is, the hydraulic cylinder 22 can close or open the passage 14b by the forward and backward movement of the cylinder rod 26. With this closing or opening, the introduction of the molten metal L into the cavity 13b is stopped or started.
[0032]
Next, a preferred embodiment of a method for producing a molded product using the tandem injection molding apparatus 20 will be described with reference to FIGS.
[0033]
First, the second cylinder 10 is urged backward to cause the cylinder rod 11 to retract, and the central mold 9 and the second mold 8 are brought into close contact with each other. Due to this close contact, the cavity 13b is formed.
[0034]
Next, the first cylinder 4 is urged forward to extend the cylinder rod 5, and the movable platen 3 is brought close to the fixed platen 2 until the first die 7 and the central die 9 come into close contact with each other. Due to this close contact, a cavity 13a having a larger volume than the cavity 13b is formed.
[0035]
Next, as shown in FIG. 2, the hydraulic cylinder 22 is urged to extend the cylinder rod 26, the tip of the cylinder rod 26 is fitted into the opening 28 of the passage 14b, and the passage 14b is closed. In this state, the molten metal L is injected from the injection mechanism 12, and the molten metal L is introduced only into the cavity 13a.
[0036]
As the molten metal L is introduced into the cavity 13a, the remaining space 30 in the cavity 13a gradually decreases. The molten metal L is introduced into the cavity 13a until the volume of the remaining space 30 is equal to the volume of the cavity 13b. In this case, each volume of the cavities 13a and 13b and the injection amount of the molten metal L per unit time are obtained in advance, and the introduction amount of the molten metal L into the cavity 13a is determined from the elapsed time after the injection of the molten metal L is started. If calculated, the volume of the remaining space 30 can be easily obtained. Or you may make it obtain | require the volume of the remaining space 30 by installing a pressure sensor in the cavity 13a, and measuring the pressure change in the cavity 13a accompanying introduction of the molten metal L with this pressure sensor.
[0037]
Then, when the volume of the remaining space 30 becomes the same as the volume of the cavity 13b, the cylinder rod 26 is moved backward to open the passage 14b as shown in FIG. 3, and the remaining space 30 and the cavity 13b are opened. Molten metal L is introduced into both.
[0038]
When the molten metal L is introduced in this way, the volume of the remaining space 30 and the volume of the cavity 13b are the same, and therefore, the filling operation of the molten metal L into the remaining cavity 13a and the cavity 13b is completed almost simultaneously. That is, as shown in FIG. 4, the filling of the molten metal L into the cavities 13a and 13b is completed almost simultaneously. When filling of the molten metal L into the cavity 13b is completed first, the cylinder rod 26 may be extended to close the passage 14b again. This is because excessive supply of the molten metal L to the cavity 13b is prevented.
[0039]
After a predetermined time has elapsed, after the molten metal L has solidified in the cavities 13a, 13b, the fixed plate 2 and the movable plate 3 are separated from each other as shown in FIG. And the center mold 9 and the second mold 8 are separated from each other, it is possible to obtain a molded product P3 having a shape suitable for the cavity 13a and a molded product P4 having a shape suitable for the cavity 13b.
[0040]
If the said manufacturing method is implemented, since the filling of the molten metal L to the cavity 13a and the cavity 13b will be completed substantially simultaneously, the introduction amount of the molten metal L in the cavity 13a will not become insufficient. Therefore, the molded product P3 having a desired shape can be reliably obtained.
[0041]
For the same reason, the molten metal L is not excessively supplied to the cavity 13b. Therefore, no burr portion is formed on the molded product P4. That is, there is no need to perform a deburring operation.
[0042]
As described above, the introduction of the molten metal L to the cavities 13a and 13b is completed almost simultaneously, so that molded products P3 and P4 having a predetermined shape can be obtained reliably. As a result, the yield and production efficiency of molded products can be improved.
[0043]
The introduction amount of the molten metal L introduced only into the cavity 13a is not uniquely determined, and differs depending on the viscosity and type of the molten metal L, the shapes and volumes of the cavities 13a and 13b, and the like. For this reason, the introduction amount of the molten metal L to the most appropriate cavity 13a, in other words, the most appropriate volume of the remaining space 30 is obtained in advance in each case. However, in most cases, the volume of the suitable residual space 30 is substantially the same as the volume of the cavity 13b.
[0044]
Further, in the injection molding apparatus 20 of the above-described embodiment, the injection mechanism 12 is installed on the fixed platen 2 side, but may be installed on the movable platen 3 side. In this case, the passage 14 b is formed in the movable platen side mold (second mold) 8.
[0045]
【The invention's effect】
As described above, according to the tandem injection molding apparatus according to the present invention, the stationary platen, the stationary platen mold installed on one side of the stationary platen, and the fixed platen are connected to each other so as to be close to or away from the stationary platen. The movable platen, a movable platen mold installed on one side of the movable platen, and the fixed platen side mold and the movable platen side mold are interposed between the fixed platen mold and the fixed platen mold. A center mold that is in close contact with the panel-side mold and the movable panel-side mold, an injection mechanism that is installed on the other side of either the fixed panel or the movable panel and injects molten metal, and the injection mechanism A first passage formed in one of the fixed platen side mold and the movable platen side mold in which the molten metal passes and the first mold formed in the central mold. A second passage communicating with the passage, and when the molded product is manufactured, the first passage Either the fixed platen side mold or the movable platen side mold in which the path is formed is brought into close contact with the central mold to form the first cavity, and the fixed platen side mold or the movable platen is formed. Either the remaining one of the panel-side molds and the center mold are brought into close contact with each other to form a second cavity having a volume smaller than that of the first cavity, and the second path includes the second path. An opening / closing mechanism is provided that stops or starts introduction of the molten metal into the second cavity by closing or opening. Accordingly, it is possible to introduce a predetermined amount of molten metal into the first cavity and then complete the filling operation of the molten metal into the remaining space and the second cavity at the same time.
[0046]
According to the method for manufacturing a molded product using the tandem injection molding apparatus according to the present invention, the second passage is closed, and only the first cavity is melted through the first passage. And then the second passage is opened and the remaining space in the first cavity and the second cavity are melted via the first passage and the second passage. At the same time, the filling of the molten metal into the first and second cavities is completed substantially simultaneously.
[0047]
Thereby, the introduction amount of the molten metal in the first cavity does not become insufficient. Moreover, the molten metal is not excessively supplied to the second cavity. As a result, a molded product having a desired shape can be reliably obtained, so that the yield and production efficiency of the molded product can be improved.
[Brief description of the drawings]
FIG. 1 is a schematic configuration explanatory diagram of a tandem injection molding apparatus according to an embodiment of the present invention.
FIG. 2 is a schematic longitudinal sectional view showing a state in which three molds provided in the tandem injection molding apparatus of FIG. is there.
FIG. 3 is a schematic longitudinal sectional view showing a state in which molten metal is further introduced into a cavity having a small volume from the state of FIG. 2;
4 is a schematic longitudinal sectional view showing a state in which molten metal is filled in two large and small cavities having different volumes in the tandem injection molding apparatus of FIG. 1. FIG.
FIG. 5 is a schematic configuration explanatory diagram of a tandem injection molding apparatus according to a conventional technique.
6 is a schematic longitudinal cross-sectional view showing a state in which the cavities having a small volume are filled with the molten metal and the cavities having a large volume are not filled with the molten metal in the tandem injection molding apparatus of FIG. 5;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1,20 ... Tandem type injection molding apparatus 2 ... Fixed platen 3 ... Movable platen 6 ... Tie bar 7 ... Fixed platen side metal mold | die (1st metal mold | die) 8 ... Movable platen side metal mold | die (2nd metal mold | die)
DESCRIPTION OF SYMBOLS 9 ... Central metal mold | die (3rd metal mold | die) 12 ... Injection mechanism 13a, 13b ... Cavity 14a, 14b ... Passage 22 ... Hydraulic cylinder 24 ... Space part 26 ... Cylinder rod 28 ... Opening part 30 ... Remaining space L ... Molten metal P1 , P2, P3, P4 ... Molded products

Claims (6)

A fixed plate,
A fixed platen mold installed on one side of the fixed plate;
A movable plate connected to the fixed plate so as to approach or separate from the fixed plate;
A movable platen mold installed on one side of the movable plate;
A central mold interposed between the fixed platen mold and the movable platen mold, and in close contact with the fixed platen mold and the movable platen mold when manufacturing a molded product;
An injection mechanism for injecting molten metal installed on the other side of either the fixed platen or the movable platen;
A first passage that is formed in one of the fixed platen mold or the movable platen mold in which the injection mechanism is installed and through which the molten metal passes;
A second passage communicating with the first passage formed in the central mold;
Comprising
At the time of manufacturing a molded product, either the fixed platen mold or the movable platen mold in which the first passage is formed and the central mold are brought into close contact with each other so that the first cavity is the first cavity. The second mold having a volume smaller than that of the first cavity is formed in communication with the passage, and the central mold is brought into close contact with the remaining one of the fixed plate side mold or the movable plate side mold. A cavity is formed in communication with the second passage ;
At the entrance of the second passage formed in the central mold, the introduction of the melt into the second passage and the second cavity is stopped or closed by closing or opening the second passage. A tandem injection molding apparatus, wherein an opening / closing mechanism is provided. The tandem injection molding apparatus according to claim 1,
The tandem injection molding apparatus, wherein the opening / closing mechanism comprises a cylinder installed in the central mold, and an opening of a second passage into which a cylinder rod of the cylinder is fitted or detached. The tandem injection molding apparatus according to claim 2,
In order to accommodate the cylinder when the second cavity is formed in either the fixed platen mold or the movable platen mold that forms the second cavity together with the central mold. A tandem injection molding apparatus characterized in that a space portion is provided. In the tandem injection molding apparatus according to claim 2 or 3,
A tandem injection molding apparatus, wherein the cylinder rod is inserted through the center of the second passage. A stationary platen, a stationary platen mold installed on one side of the stationary platen, a movable plate connected to the stationary plate so as to be close to or away from the stationary platen, and a movable platen side installed on one side of the movable platen A middle mold interposed between the mold and the stationary platen mold and the movable platen mold, and in close contact with the fixed platen mold and the movable platen mold when manufacturing a molded product; Either an injection mechanism for injecting molten metal installed on the other side of either the fixed platen or the movable platen, and either the fixed platen die or the movable platen die on which the injection mechanism is installed A first passage through which the molten metal passes, and a second passage communicating with the first passage formed in the central mold, and at the time of manufacturing a molded product, Either the fixed platen mold or the movable platen mold in which the first passage is formed How a together with the first cavity and the central mold and is in close contact is formed to communicate with the first passage, either a central gold remaining of the stationary platen side die or the movable platen side mold A second cavity having a volume smaller than that of the first cavity is formed in communication with the second passage, and is formed at the entrance of the second passage formed in the central mold. A tandem injection molding apparatus provided with an opening / closing mechanism for stopping or starting the introduction of the molten metal into the second passage and the second cavity by closing or opening the second passage is used. A method of manufacturing a molded article,
Closing the second passage and introducing the molten metal only to the first cavity through the first passage;
Opening the second passage and simultaneously introducing molten metal into the remaining space of the first cavity and the second cavity via the first passage and the second passage;
A method for producing a molded article using a tandem injection molding apparatus. In the manufacturing method of the molded article according to claim 5,
The opening of the second passage is performed by energizing the opening / closing mechanism when the volume of the remaining space of the first cavity becomes equal to the volume of the second cavity. A method of manufacturing a molded product using a tandem injection molding apparatus.

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