JP2016203474A - Molding die and in-mold coating molding method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress occurrence of burr which is produced on a part surface.SOLUTION: After a resin 201 is injected and solidified, an interval between a first mold 101 and a second mold 102 is opened by a prescribed amount while keeping a state in which a third mold 103 is pressed to the second mold 102, so that, even when the resin 201 is shrunk, the third mold 103 can move accompanied with the shrinkage, and production of a clearance due to shrinkage is suppressed. Thus, even when a coating having good fluidity is used, occurrence of burr can be suppressed.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an in-mold coating molding method for integrally molding a coating film on the surface of a resin molded product and a molding die used therefor.

  In-mold coating molding method (hereinafter referred to as “IMC”) is a method in which paint is injected between the surface of a resin molded product molded in a mold and the cavity surface of the mold, and then the paint is put into the mold. This is a molding method for producing an integrally molded product in which the coating film is in close contact with the resin molded product. The advantage of IMC is that the cost can be reduced by reducing the molding process, and in the case of spray coating, the unevenness of the molded product remains as it is, but in the case of IMC, the mold surface is transferred to the surface of the paint. Therefore, the point which can obtain a favorable external appearance is raised. Conventionally, IMC has been performed for the production of a molded product of a thermosetting resin, but in recent years, as described in Patent Document 1, it has also been applied to molding of a thermoplastic resin.

Hereinafter, a molding die and IMC shown in Patent Document 1 will be described as conventional in-mold coating with reference to FIGS.
FIG. 10 is a view showing a mold structure of Patent Document 1, FIG. 11 is an enlarged view of a main part showing the structure of a subcavity of the mold structure described in Patent Document 1, and FIG. 13 is a cross-sectional view of the main part of the mold explaining the molding method for each process, FIG. 13 is a schematic diagram of the main part explaining the state of the resin in the groove during resin injection in Patent Document 1, and FIG. 14 is when the mold is opened in Patent Document 1 It is the principal part outline figure explaining the mode of resin of the groove part.

  As shown in FIG. 10, in the mold of Patent Document 1, a first mold 601 and a second mold 602 constitute a cavity 603. A sub-cavity 604 communicating with the cavity 603 is formed on the part surface of the second mold 602, and a groove 605 communicating with the sub-cavity 604 is further formed. The shapes of the subcavity 604 and the groove portion 605 are not particularly limited, and the groove portion 605 can be configured to be orthogonal to the subcavity 604 as shown in FIG. In this case, the groove portion 605 needs to have a standing wall so that the forming direction of the groove 605 has a draft of 0 ° with respect to the direction in which the first mold 601 moves at the time of releasing so as not to hinder the releasing. is there. When performing in-mold coating using the first mold 601 and the second mold 602, first, a resin molded product is molded. Next, a predetermined interval is opened between the first mold 601 and the second mold 602, and a predetermined amount of paint is injected into the cavity 603 by the paint injection machine 606, and then the first mold 601 and the second mold 602 are injected. Close the mold 602.

  FIG. 12 explains the state of molding of the resin and paint in the steps from resin molding to paint injection and mold clamping described above for the subcavity 604 and the groove 605 having the shape shown in FIG. First, the molding resin 607 is filled in the cavity 603, the sub-cavity 604, and the groove 605. In this state, the first mold 601 and the second mold 602 are opened by a predetermined width to create a gap 609. Next, paint 608 is poured into the gap 609. Then, the mold is clamped so that the paint 608 is evenly spread over the surface of the molding resin 607. At this time, the excessive paint 608 is accommodated in the groove 605, and the molding resin 607 is not deformed and does not flow out to the mold part surface.

JP 2001-38737 A

  However, in the mold structure described in Patent Document 1, the resin filled in the groove 605 starts to shrink immediately after filling, and a slight clearance is generated between the resin and the groove 605. . 13 is an enlarged view of the groove portion in the injection molding step of FIG. 12, and FIG. 14 is an enlarged view of the groove portion in the mold opening step of FIG. By performing the mold opening process, the molding resin 607 formed in the groove 605 is released from the second mold 602, and the mold unevenness 701 is obtained even when the draft angle of the standing wall is set to 0 °. A clearance 703 is generated by the unevenness 702 formed on the surface of the molding resin 607. Therefore, when the paint is injected and clamped, the paint 608 accommodated in the groove 605 and the paint 608 (see FIG. 12) accommodated in the clearance 703 are transmitted through the clearance 703 depending on the characteristics of the paint. Then, it flows out to the mold part surface, burrs are generated, and the burrs remain in the mold. Since burrs remain on the mold part surface, regular mold maintenance is required, making continuous molding difficult.

  This invention solves the said subject, and it aims at suppressing the burr | flash which generate | occur | produces on a part surface.

  In order to achieve the above object, a molding die of the present invention includes one or more first molds that are fixed molds, one or more second molds that are movable molds, and the second mold. A third mold that can move in accordance with the movement, a cavity surrounded by the first mold, the second mold, and the third mold, and a cylinder that presses the third mold against the second mold A sprue formed in the first mold and injecting resin into the cavity, and an injector formed in the second mold and injecting paint into the cavity. The resin is placed in the outer periphery of the cavity, and after the mold is clamped, the resin is injected into the cavity and the resin is hardened. Then, the second mold moves and the third mold becomes the second mold. A gap is formed between the resin that has been pressed and cured and the second mold, The paint serial gap is injected, after the second die is moved in the direction of the first mold, the coating material is characterized in that it is solidified.

  Further, the in-mold coating forming method of the present invention is in accordance with the movement of one or more first molds that are fixed molds, one or more second molds that are movable molds, and the second mold. A step of clamping the first mold, the second mold, and the third mold when performing in-mold coating using a movable third mold, and the first mold, the first mold, A step of injecting a resin into a cavity surrounded by two molds and the third mold, a step of curing the resin, and the second mold in a state where the third mold is in pressure contact with the second mold. A step of forming a gap between the cured resin by moving the mold and the second mold, a step of injecting paint into the gap, and a direction of the second mold in the direction of the first mold And a step of solidifying the paint, wherein the third mold is disposed on the outer periphery of the cavity. The features.

  As described above, after the resin has been injected and solidified, the resin is removed by opening a predetermined distance between the first mold and the second mold while the third mold is pressed against the second mold. Even when contracted, the third mold moves along with the contraction and suppresses the generation of clearance due to the contraction. Therefore, even when a paint having good fluidity is used, the generation of burrs can be suppressed.

The figure which shows the structure of the IMC injection mold of this invention Sectional drawing explaining operation | movement of the metal mold | die in each process of the in-mold coating molding method of this invention Sectional drawing explaining operation | movement of the metal mold | die in each process of the in-mold coating molding method of this invention Sectional drawing explaining operation | movement of the metal mold | die in each process of the in-mold coating molding method of this invention Sectional drawing explaining operation | movement of the metal mold | die in each process of the in-mold coating molding method of this invention Sectional drawing explaining operation | movement of the metal mold | die in each process of the in-mold coating molding method of this invention Schematic explaining the configuration of the cavity periphery during resin injection in the in-mold coating molding of the present invention The figure explaining the structure of the clearance gap between resin and metal mold | die in the metal mold | die coating molding of this invention The principal part enlarged view which shows the structure of the molding die in Embodiment 2 The figure which shows the metal mold | die structure of patent document 1 The principal part enlarged view which shows the structure of the subcavity of the metal mold | die structure described in patent document 1 Main part sectional drawing of the metal mold | die explaining the coating method in a metal mold | die of patent document 1 for every process Schematic diagram of relevant parts for explaining the state of the resin in the groove at the time of resin injection in Patent Document 1. Schematic diagram of relevant parts for explaining the state of the resin in the groove when the mold is opened in Patent Document 1.

Hereinafter, embodiments of an in-mold coating forming method and a forming mold according to the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a view showing a configuration of an IMC injection mold according to the present invention.

  The mold is composed of a first mold 101 and a third mold 103 on the fixed side, and a second mold 102 on the movable side. The first mold 101 is attached to the template 104. The third mold 103 can be slid on the outer periphery of the first mold 101 by the cylinder 105 and is pressed against the second mold 202.

  A convex cavity surface 106 is formed in the first mold 101. A concave cavity surface 107 is formed in the second mold 102. In the clamped state, the first mold 101, the second mold 102, and the third mold 103 form a cavity 108 of the product shape portion. The first mold 101 and the mold plate 104 are provided with a sprue 109 for flowing resin into the cavity 108, and the second mold 102 is provided with an injector 110 for injecting paint onto the product external surface.

The in-mold coating forming method using the forming mold shown in FIG. 1 will be described in detail with reference to FIGS.
2-6 is sectional drawing explaining operation | movement of the metal mold | die in each process of the in-mold coating molding method of this invention. FIG. 7 is a schematic diagram for explaining the configuration of the cavity peripheral portion at the time of resin injection in the in-mold coating of the present invention, and FIG. 8 explains the configuration of the gap between the resin and the mold in the in-mold coating of the present invention. FIG. 9 and FIG. 9 are enlarged views of main parts showing the configuration of the molding die in the second embodiment.

First, FIG. 2 shows a state in which the first mold 101, the third mold 103, and the second mold 102 are in the mold opening position.
Next, the first mold 101, the third mold 103, and the second mold 102 are clamped. At this time, the third mold 103 is pressed against the second mold 102 by the cylinder 105. FIG. 1 is a diagram showing this state.

  Next, as shown in FIG. 3, the melted thermoplastic resin enters the cavity 108 surrounded by the first mold 101, the second mold 102, and the third mold 103 from the cylinder of the molding machine through the sprue 109. Resin 201 is injected. FIG. 7 is an enlarged view of the outer peripheral portion of the molded product in a state in which the thermoplastic resin 201 is filled in FIG. The clamping force of the third mold 103 by the cylinder 105 is made smaller than the molding pressure of the thermoplastic resin 201 to intentionally generate a gap 302 between the second mold 102 and the third mold 103. As a result, the thermoplastic resin 201 enters the gap 302, and a burr 301 made of the thermoplastic resin 201 is generated on the part surface. At this time, the thickness L of the burr 301 is set to about 0.1 mm, and the clamping force is adjusted so that the burr 301 is not peeled off from the end surface of the product. After this process, the mold is cooled in a clamped state, and the thermoplastic resin 201 is solidified. This burr 301 is not a problem because it does not remain in the mold by sticking to the product.

  Next, as shown in FIG. 4, after the thermoplastic resin 201 is solidified, the second mold 102 is slightly opened by the function of the injection molding machine. At this time, a gap 203 is formed between the thermoplastic resin 201 and the second mold 102 in the molded product forming portion sandwiched between the first mold 101 and the second mold 102. The third mold 103 is pressed against the second mold 102 by the cylinder 105. Therefore, the surplus portion 202 made of the thermoplastic resin 201 formed between the third mold 103 and the second mold 102 and formed around the molded product forming portion is pressed against the second mold 102. In this state, the mold moves following the movement of the mold opening, and no gap is formed between the third mold 103 and the second mold 102. FIG. 8 shows an enlarged view of the outer periphery of the molded product in the state of FIG. Since the thermoplastic resin 201 is stuck to the convex cavity surface 106 by contraction, the surplus portion 202 is deformed within the elastic range of the thermoplastic resin 201, and the concave cavity surface 107 of the second mold 102 is deformed. A gap 203 is formed between the thermoplastic resin 201 and the thermoplastic resin 201. Such deformation can be deformed even if it is completely solidified because the opening amount is very small. The formation of the gap is preferably performed at the moment when the temperature allowing the protrusion is reached. Since the gap 203 is pressed and fixed to the second mold 102 by the third mold 103, the gap 203 has a feature that the gap 203 is smaller at the outer peripheral portion than at the center of the molded product. It is also effective to cause a vacuum break (filling with air) between the cavity surface 107 and the thermoplastic resin 201 by ejecting a gas from the injector 110 in order to reliably open the gap 203.

  Next, as shown in FIG. 5, a thermosetting paint 204 is injected into the gap 203 from the injector 110. Although the paint 204 has very good fluidity, the third mold 103 is pressed against the second mold 102 by the cylinder 105, so that even if the surplus portion 202 contracts, the second mold 102 and the second mold 102 are pressed. Since there is no gap between the three molds 103, the paint 204 does not flow out. Further, the gap 203 through which the coating material 204 flows is thinner toward the outer peripheral portion, and when the coating material 204 is injected, it is filled from the outer peripheral portion by capillary action. Further, since the gap 203 in the outer peripheral portion is thin and heat is easily transmitted, the thermosetting paint 204 is easily cured, and the occurrence of burrs due to the paint 204 is also suppressed.

  Next, as shown in FIG. 6, re-clamping is performed after the coating is injected and before curing. The paint 204 is in a state where pressure is applied to the surface of the thermoplastic resin 201 by being clamped. Therefore, the surface of the cavity surface 107 of the second mold 102 is transferred to the surface of the paint 204, and the appearance of the paint 204 is improved. Thereafter, the paint 204 is heated by the temperature of the mold, and curing is accelerated and solidified.

  As described above, the formation area of the molded product is formed by the first mold 101 and the second mold 102, the peripheral part of the formation area is formed by the third mold 103 and the second mold 102, and the second When the mold 102 is opened and the gap 203 for injecting the paint 204 is formed, the third mold 103 follows the second mold 102 and moves to follow the third mold 103 even if the resin 201 contracts. By not forming a gap with the second mold 102, the injected paint 204 is suppressed from flowing out to the part surface between the third mold 103 and the second mold 102, so that the part surface The formation of burrs in the paint 204 is suppressed. Since the occurrence of burrs is suppressed, periodic mold maintenance is not required, and continuous molding becomes possible. Further, the burr 301 made of the resin 201 is formed between the third mold 103 and the second mold 102, whereby the resin 201 is firmly attached to the third mold 103 and the second mold 102 by the burr 301. Therefore, the gap 203 is not formed between the third mold 103 and the second mold 102 more reliably, and the injected paint 204 is transferred between the third mold 103 and the second mold 102. Outflow to the part surface in between is more reliably suppressed, and formation of burrs of the paint 204 on the part surface is more reliably suppressed. Furthermore, since the clearance 203 becomes narrower toward the outside of the formation region at the end of the clearance 203, the coating 204 is accelerated in the narrower region, and thus the outflow of the coating 204 at the end of the clearance 203 is further suppressed. The occurrence of burrs in the paint 204 is suppressed.

  In the above description, the third mold 103 is provided at a position where the peripheral portion of the formation region is sandwiched between the second mold 102, but may be provided at a position in contact with the periphery of the cavity 108. When the third mold 103 and the second mold 102 come into contact with each other with sufficient pressure around the cavity 108, the resin 204 is suppressed from flowing out to the part surface. The cavity 108 may be formed by three molds, ie, the first mold 101, the second mold 102, and the third mold 103, but may be formed by four or more molds. In this case as well, the peripheral part of the cavity 108 may be configured while the third mold 103 follows the fixed mold.

  When it is necessary to further suppress the generation of burrs, only the outer peripheral portion of the product may be partially heated by the heating device 111 when the coating material 204 is injected from the injector 110. Thereby, hardening of the coating material 204 of a product outer peripheral part is accelerated | stimulated, it can suppress that the coating material 204 flows out to a part surface, and can suppress generation | occurrence | production of the burr | flash of the coating material 204 more.

(Embodiment 2)
Next, the structure of the molding die in Embodiment 2 is demonstrated using FIG.
FIG. 9 is an enlarged view of a main part showing the configuration of the molding die in the second embodiment.

  When it is necessary to further suppress the occurrence of burrs, the molding die in the second embodiment is located at a position corresponding to the outer peripheral portion of the product as shown in FIG. 9 with respect to the molding die in the first embodiment. A texture 501 having a continuous fine uneven shape is attached. That is, in the molding die in the second embodiment, the embossed surface 501 is provided on the cavity surface 107 in the outer peripheral portion of the region where the product of the second die 102 is formed. Thereby, irregularities 502 are also formed on the surface of the thermoplastic resin 201. Then, when the mold is opened after the thermoplastic resin 201 is solidified, the texture 501 and the unevenness 502 are exposed in the gap 203 on the cavity surface 107 of the second mold 102 and the surface of the thermoplastic resin 201. If the coating material 204 is poured in this state, the contact area between the second mold 102 and the thermoplastic resin 201 and the coating material 204 increases due to the embossments 501 and the projections and depressions 502, and the curing efficiency of the coating material 204 increases. Is suppressed, and the occurrence of burrs in the paint 204 is suppressed.

  As described above, the present invention has been described by using the example of the embodiment, but there are many other specific structures that realize the gist of the present invention, and modifications are easy for those belonging to the industry, It does not depart from the invention.

  INDUSTRIAL APPLICATION This invention can suppress the burr | flash which generate | occur | produces on a part surface, and is useful for the molding die used for it, the molding die used for it, etc. which integrally coat a coating film on the surface of a resin molded product.

101 First mold 102 Second mold 103 Third mold 104 Mold plate 105 Cylinder 106 Cavity surface 107 Cavity surface 108 Cavity 109 Sprue 110 Injection machine 111 Heating device 201 Thermoplastic resin 202 Remaining part 203 Crevice 204 Paint 301 Burr 302 Clearance 501 Grain 502 Unevenness 601 First mold 602 Second mold 603 Cavity 604 Subcavity 605 Groove 606 Paint injection machine 607 Molding resin 608 Paint 609 Clearance 701 Unevenness 702 Unevenness 703 Clearance

Claims (8)

One or more first molds which are fixed molds;
One or more second molds that are movable,
A third mold that can move in accordance with the movement of the second mold;
A cavity surrounded by the first mold, the second mold, and the third mold;
A cylinder that presses the third mold against the second mold;
A sprue formed in the first mold and injecting resin into the cavity;
An injection machine that is formed in the second mold and injects paint into the cavity, and the third mold is disposed on the outer periphery of the cavity, and the resin is injected into the cavity in a clamped state. After the resin is cured, the second mold moves and a gap is formed between the second mold and the resin that is cured by pressing the third mold against the second mold. The molding die is characterized in that the coating material is solidified after the coating material is injected into the gap and the second die moves in the direction of the first die.   The molding die according to claim 1, wherein the gap is narrower toward a peripheral portion of the cavity.   The molding according to claim 1 or 2, wherein the injector is capable of injecting a gas into the cavity, and injecting the gas into the cavity before injecting the paint. Mold. A heating device in the vicinity of the periphery of the cavity;
The molding die according to any one of claims 1 to 3, wherein a peripheral portion of the cavity is heated when the paint is injected. Inner mold coating using one or more first molds that are fixed molds, one or more second molds that are movable molds, and a third mold that can move in accordance with the movement of the second molds When molding
Clamping the first mold, the second mold, and the third mold;
Injecting resin into a cavity surrounded by the first mold, the second mold, and the third mold;
Curing the resin;
Forming a gap between the second mold and the resin cured by moving the second mold in a state where the third mold is in pressure contact with the second mold;
Injecting paint into the gap;
Moving the second mold in the direction of the first mold;
And a step of solidifying the paint, wherein the third mold is disposed on an outer periphery of the cavity.   6. The in-mold coating method according to claim 5, wherein the gap becomes narrower as it approaches the periphery of the cavity.   8. The in-mold coating method according to claim 6, wherein the gas is injected into the cavity after the gap is formed and before the paint is injected.   The in-mold coating forming method according to any one of claims 5 to 7, wherein a peripheral portion of the cavity is heated when the paint is injected.

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