JP5936983B2 - Stack mold injection compression molding method - Google Patents

Description

  The present invention relates to a stack mold injection compression molding method in which injection compression molding is performed in a stack mold injection mold that can mold a plurality of molded products with a single mold.

  2. Description of the Related Art Conventionally, injection molded products molded into a predetermined shape by injecting molten resin into a cavity in a mold and solidifying by cooling are used in all fields. As a kind of injection mold used at this time, a stack mold injection mold capable of forming a plurality of molded products with one mold has been developed. According to the stack mold injection mold, it is possible to simultaneously mold a plurality of molded articles with the same clamping force as that of general injection molding (hereinafter referred to as single injection molding) in which one molded article is molded with one mold. Has the advantage. That is, a plurality of molded products can be manufactured at the same time with a production cost (running cost) equivalent to that of single injection molding, and productivity can be greatly improved as compared with the prior art. As a result, the cost per molded product is also reduced.

  For example, Patent Document 1 has been proposed as such a stack mold injection mold. In Patent Document 1, a fixed mold, a movable mold, and an intermediate mold that is slidable between the fixed mold and the movable mold are provided, and a first is provided between the fixed mold and the intermediate mold. The second cavity is formed between the intermediate mold and the movable mold. A primary runner is provided in the fixed mold for communicating the molten resin supply nozzle and the first cavity, and the first cavity and the second cavity are communicated in the intermediate mold. A secondary runner is provided. In addition, the molten resin injected into the first cavity through the primary runner is also injected into the second cavity as it is through the secondary runner. That is, in Patent Document 1, the molten resin is simultaneously injected into the first cavity and the second cavity as in the prior art.

  On the other hand, an injection compression molding method is also disclosed in which a compression force is applied to mold a molded product before the molten resin injected into the cavity is cooled and solidified. According to this, the general injection molding which molds with the filling pressure of the molten resin by molding the molded product while receiving the compressive force when the mold is clamped (hereinafter referred to as filling pressure injection molding). As a result, the surface property unevenness of the molded product can be suppressed, and a molded product with high quality can be obtained. For example, Patent Document 2 has been proposed as such an injection compression molding method. In Patent Document 2, a compression force is applied to the molten resin injected into the cavity by injecting the molten resin in a half-tight state immediately before the fully-tightened state after the mold is completely clamped and then completely clamping the mold. Is acting.

Japanese Patent Laid-Open No. 05-278087 JP 2004-66728 A

  As described above, each of the stack mold injection mold and the injection compression molding has unique advantages. Therefore, in order to obtain the advantages of both, injection compression molding may be performed as in Patent Document 2 in a stack mold injection mold as in Patent Document 1. However, when patent document 1 and patent document 2 are simply combined, it is necessary to simultaneously apply a clamping force higher than that of filling pressure injection molding to a plurality of cavities. This doubles the total mold clamping force depending on the number of cavities, so that the advantage of the stack mold injection mold that can simultaneously mold a plurality of molded products at the same production cost as single injection molding is lost.

  Therefore, in order to perform injection compression molding without impairing the advantages of the stack mold injection mold, it is conceivable to shift the timing of compression force (complete tightening timing) applied to each cavity. However, if the molten resin is injected into a plurality of cavities at the same time as in Patent Document 1 and the final fastening timing is changed, the time from when the molten resin is injected into the cavity until it is solidified varies. This causes variations in the quality of the molded product obtained in each cavity. In the worst case, a defective product may be generated, and the meaning of combining the stack mold injection mold and the injection compression molding is lost.

  Therefore, the present invention solves such problems, and its purpose is to obtain each molded product obtained simultaneously with injection compression molding using a stack mold injection mold without increasing production cost more than necessary. It is an object of the present invention to provide a stack mold injection compression molding method that does not cause variations in quality.

  As a means for that, the present invention comprises a fixed mold, a movable mold, and an intermediate mold that can slide between the fixed mold and the movable mold, and the fixed mold and the intermediate mold, In a stack mold injection mold in which a first cavity is formed between the intermediate mold and the movable mold, a compressive force is applied to the molten resin injected into each cavity. A stack mold injection compression molding method that cools and solidifies while acting, after injecting the molten resin into one of the first and second cavities and performing injection compression molding, and then the other cavity It is characterized by injecting molten resin into the injection compression molding.

  According to this, the injection timing of the molten resin into each cavity is shifted, and since the injection compression molding is performed in one cavity and then the injection compression molding is performed in the other cavity, the solidification is performed after the molten resin is injected in each cavity. The time to do is uniform. Thereby, it is possible to avoid variations in quality such as surface properties of each molded product to be obtained.

  At this time, a primary runner that communicates with a nozzle for supplying a molten resin is provided in the fixed mold, and the intermediate runner communicates with the primary runner in a fully-tightened state of the intermediate mold and the fixed mold. A secondary runner that communicates with each of the first and second cavities via a valve gate capable of controlling the injection timing of the molten resin, and then to the second cavity. After injecting the molten resin and performing injection compression molding, it is preferable that the molten resin is then injected into the first cavity and injection compression molded.

  According to this, the location and timing for injecting the molten resin can be freely set by controlling the valve gate. If the primary runner and the secondary runner communicate with each other when the intermediate mold and the fixed mold are completely tightened, the primary runner and the secondary runner are half-tightened between the intermediate mold and the fixed mold. A slight gap (hereinafter referred to as a discarded runner) is generated around the communication portion with the runner, and the discarded runner is filled with molten resin. In this case, if the injection compression molding is first performed in the first cavity, the molten resin collected in the discarded runner starts to solidify, so that the injection compression moldability in the second cavity is hindered. In order to avoid this, it is necessary to bother removing the resin solidified by the discarded runner before injection molding in the second cavity following the first cavity, and productivity is lowered. Therefore, the above-described problems can be avoided if the configuration is such that the injection compression molding is first performed in the second cavity and then the injection compression molding is performed in the first cavity.

  According to the present invention, it is possible to perform injection compression molding with a stack mold injection mold without increasing production costs more than necessary, and there is no variation in quality in each molded product obtained at the same time.

It is a schematic diagram of the shaping | molding die of a full open state. It is a schematic diagram which shows the state which has injected the molten resin to the 2nd cavity. It is a schematic diagram which shows the state currently compression-molded in the 2nd cavity. It is a schematic diagram which shows the state which has injected the molten resin to the 1st cavity. It is a schematic diagram which shows the state currently compression-molded in the 1st cavity.

  Hereinafter, representative embodiments of the present invention will be described. As shown in FIG. 1 and the like, the mold used in this embodiment is a fixed mold 10, a movable mold 11, and an intermediate mold that can slide between the fixed mold 10 and the movable mold 11. 12 between the fixed mold 10 and the intermediate mold 12 (both facing surfaces) and between the intermediate mold 12 and the movable mold 11 (both facing surfaces). It is a stack mold injection mold in which one cavity 20 and a second cavity 21 are formed. In the present embodiment, a plurality of first and second cavities 20 and 21 are provided between the fixed mold 10 and the intermediate mold 12 and between the intermediate mold 12 and the movable mold 11 ( 2 places).

  The fixed mold 10 is provided with a primary runner 15 that communicates with a nozzle 14 to which a molten resin is supplied. The movable mold 11 is slidably disposed at a position facing the fixed mold 10 via the intermediate mold 12. In the intermediate mold 12, a secondary runner 16 is provided, one end of which directly communicates with the primary runner 15 in a state where the intermediate mold 12 and the fixed mold 10 are completely tightened. The secondary runner 16 extends in a branching manner in a plurality of directions in the intermediate mold 12, and the other ends communicate with the cavities 20 and 21, respectively. A valve gate 30 is provided at the other end of the secondary runner 16 (communication portion with each of the cavities 20 and 21). As shown in FIG. 2, the valve gate 30 includes a sealing pin (valve) 32 that can move forward and backward with respect to the valve gate injection portion 31. By opening and closing the injection unit 31, the injection timing of the molten resin can be controlled. Reference numeral 17 denotes a tie rod that guides the sliding movement of the movable mold 11 and the intermediate mold 12.

  In addition, a method for injection compression molding of a resin molded product using the mold will be described. First, from the fully opened state shown in FIG. 1, as shown in FIG. 2, the intermediate mold 12 is completely clamped (completely tightened) with respect to the fixed mold 10, and the primary runner 15 and the secondary runner 16 are connected. Direct communication. On the other hand, at this time, the intermediate mold 12 and the movable mold 11 are not completely tightened, and the half-tightened state immediately before the fully-tightened state (the intermediate mold 12 and the movable mold 11 are slightly opened compared to the fully-tightened state). State). After that, the molten resin is injected from the nozzle 14 through the primary runner 15 and the secondary runner 16 only to each second cavity 21. At this time, since the primary runner 15 and the secondary runner 16 are in direct communication with each other, the molten resin does not accumulate in the vicinity of the communication portion between the primary runner 15 and the secondary runner 16.

  When a sufficient amount of molten resin can be filled in each second cavity 21 in the half-tightened state between the intermediate mold 12 and the movable mold 11, as shown in FIG. 3, the intermediate mold 12 and the movable mold 11 To complete compression molding. That is, a compressive force acts on the molten resin filled in each second cavity 21, and the movable mold 11 is cooled in the compressed state to solidify the molten resin. Thereby, it becomes a high-quality molded article having a good surface property.

  When injection compression molding can be performed in each second cavity 21, as shown in FIG. 4, the fixed mold 10 and the intermediate mold 12 are slightly opened to be half-tightened, and then each first cavity is in turn. The molten resin is injected into 20. At this time, a slight gap (discarding runner) 22 is generated around the communication portion between the primary runner 15 and the secondary runner 16, and the molten resin flows into the discarding runner 22. During the injection compression molding in the first cavity 20, the intermediate mold 12 and the movable mold 11 are held in a completely tightened state, and the second cavity 21 side is maintained in a cooled state. ing.

  Then, when a sufficient amount of molten resin can be filled in each first cavity 20 in the half-tightened state between the fixed mold 10 and the intermediate mold 12, as shown in FIG. 5, the fixed mold 10 and the intermediate mold 12 and complete compression molding. That is, a compressive force acts on the molten resin filled in each first cavity 20, and the fixed mold 10 is cooled in the compressed state to solidify the molten resin. Thereby, it becomes a high-quality molded article having a good surface property. In addition, since the molten resin collected in the discarded runner 22 has sufficient fluidity when the fixed mold 10 and the intermediate mold 12 are completely tightened, the fixed mold 10 and the intermediate mold 12 As a result of the final tightening, the primary runner 15 and the secondary runner 16 are almost swept away, and almost no molten resin remains in the discarded runner 22.

  If injection compression molding can be performed in each first cavity 20, the molds 10, 11, and 12 are finally fully opened, and the molded product may be taken out from the cavities 20 and 21. The subsequent steps are repeated from the state shown in FIG.

(Modification)
As mentioned above, although typical embodiment of the stack mold injection compression molding method concerning this invention was described, it is not restricted to this, A various deformation | transformation is possible in the range which does not deviate from the summary of this invention. In particular, as long as the molding method is one in which the molten resin is injected into one of the first and second cavities and injection compression molded, and then the molten resin is injected into the other cavity and injection compression molded. There are various variations in the detailed configuration of the stack mold injection compression mold used here.

  For example, in the above embodiment, the plurality of (two places) first and second cavities 20 and 21 are provided, but only one place may be provided. Alternatively, three or more locations can be provided.

  Further, although the problem of the discarded runner 22 occurs, it is also possible to perform injection compression molding in the second cavity 21 after injection compression molding in the first cavity 20, contrary to the above embodiment.

  When the fixed mold 10 and the intermediate mold 12 or the intermediate mold 12 and the movable mold 11 are in the half-tightened state, the fixed mold 10 and the intermediate mold 12 are movable between the fixed mold 10 and the intermediate mold 12. It is also possible to adopt a configuration in which a stopper is interposed between the mold 11. In this case, the stopper is disposed so as to be movable back and forth in a direction perpendicular to the sliding direction of each mold, and is controlled so as to advance between the molds only when the half-tightened state is set, and to retreat in other states.

  Further, a primary runner 15 whose one end communicates with the nozzle 14 is also branched in a plurality of directions in the fixed mold 10, one end of the other end can communicate with the secondary runner 16, and the other end is a valve gate. It is also possible to communicate with the first cavity 20 via In this case, one end of the secondary runner 16 in the intermediate mold 12 can communicate with the primary runner 15 and the other end only needs to communicate with only the second cavity 21 via the nozzle gate.

10 fixed mold 11 movable mold 12 intermediate mold 14 nozzle 15 primary runner 16 secondary runner 20 first cavity 21 second cavity 22 discarded runner 30 valve gate 31 valve gate injection part 32 sealing pin

Claims (2)

A fixed mold, a movable mold, and an intermediate mold slidable between the fixed mold and the movable mold,
A first cavity is formed between the stationary mold and the intermediate mold;
In a stack mold injection mold in which a second cavity is formed between the intermediate mold and the movable mold, the stack mold injection is made to cool and solidify while applying a compressive force to the molten resin injected into each cavity. A compression molding method,
In the fixed mold, a primary runner communicating with a nozzle for supplying a molten resin is provided,
In the intermediate mold, a secondary runner communicating with the primary runner in a state where the intermediate mold and the fixed mold are completely fastened is provided,
The secondary runner communicates with each of the first and second cavities via a valve gate capable of controlling the injection timing of the molten resin,
In a state where the fixed mold and the intermediate mold are half-tightened, a discarded runner is formed between the primary runner and the secondary runner,
Injecting molten resin into one of the first and second cavities and performing injection compression molding, then injecting molten resin into the other cavity and performing injection compression molding, Stack mold injection compression molding method. After injection compression molding by injecting a pre-Symbol molten resin into the second cavity, and then characterized by molding injection compression by injecting a molten resin into said first cavity, stack mold according to claim 1 Injection compression molding method.

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