JP2013123844A - Composite molded article, and method for molding the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite molded article which does not generate burrs when molding a secondary molded article.SOLUTION: In a composite molded article obtained by molding a secondary molded article 3 on a primary molded article 2 molded in advance, the primary molded article 2 includes a bank-like part 6 partitioning the primary molded article 2 into a part (A) which protrudes from a surface to be overlapped to the secondary molded article 3, and the other part, and the bank-like part 6 has a size and shape to abut on an inner surface of a mold for molding the secondary molded article. The bank-like part 6 may be constituted to have such a shape that the range, where the fracture strain is generated by being pressed with the mold during molding the secondary molded article 3, does not reach a surface opposite to the bank-like part 6.

Description

  The present invention relates to a composite molded body in which a secondary molded body is overlaid and molded on a preformed primary molded body.

  There is known a composite molded body in which a resin molded body (primary molded body) molded in advance is placed in a mold and another resin molded body (secondary molded body) is molded on the surface of the primary molded body. . For example, if the color of the resin forming the primary molded body and the secondary molded body is changed, a composite molded body having excellent design can be formed (Patent Document 1).

  Also, the primary molded body can be molded as a hard resin, the secondary molded body can be molded as a soft resin, and the secondary molded body can function as a cushion member or a seal member. For example, Patent Document 2 describes that a seal member (secondary molded body) is formed on an opening end surface of a casing (primary molded body). Moreover, thermoplastic elastomers (TPE) such as polyester-based thermoplastic elastomers are exemplified as a material for the seal member (secondary molded body).

  The elastomer that functions as the seal member is not limited to a thermoplastic elastomer. The seal member can also be formed of a reaction curable elastomer such as silicone rubber. Silicone rubber is liquid at room temperature and can be LIM-molded (Liquid Injection Molding). Further, according to LIM molding, a complicated shape can be molded with high accuracy. Therefore, if silicone rubber is LIM-molded, a complicated-shaped sealing member can be formed with high accuracy. In addition, the method and apparatus which LIM molds silicone rubber are already known (for example, patent document 3).

JP 2002-187166 A JP 2011-136457 A JP 2011-88381 A

  In the composite molded body, due to the molding accuracy (variation in dimensions and shape) of the primary molded body and deformation after molding, it is unexpected between the mold for molding the secondary molded body and the primary molded product. There may be gaps. The resin of the material of the secondary molded body may flow into the gap, and so-called burrs may occur. The burr not only impairs the aesthetic appearance of the composite molded body, but also may impair the function. For example, when the secondary molded body constitutes a seal member, the waterproofness is impaired if there are burrs. For this reason, the burrs are physically removed after the molding, but this burr removal operation impairs the productivity of the composite molded body.

  This invention is made | formed in view of such a situation, and it aims at providing the composite molded object which a burr | flash does not produce at the time of shaping | molding of a secondary molded object.

  In order to achieve the above object, a composite molded body according to the present invention is a composite molded body formed by stacking a secondary molded body on a primary molded body, wherein the primary molded body is raised from the surface and the secondary molded body is A bank-shaped part that divides a part that overlaps the molded body and the other part is provided, and the bank-shaped part has a size and a shape that abuts against an inner surface of a mold that molds the secondary molded body. .

  According to the present invention, since the primary formed body is provided with the bank-shaped portion, the material resin is blocked by the bank-shaped portion when the secondary molded body is molded. As a result, the leakage of the material resin is prevented, and the occurrence of burrs can be prevented. Therefore, it is not necessary to remove burrs in the subsequent process, and the productivity of the composite molded body is improved.

It is sectional drawing of the composite molded object which shows embodiment of this invention. It is sectional drawing of a primary molded object. It is sectional drawing which shows the state which inserted the primary molded object in the metal mold | die for secondary molding. It is a figure explaining the procedure to determine the shape and dimensions of the bank, (a) the actual shape of the bank, (b) the structural analysis model of the bank, (c) the structural analysis The constraint condition and load condition of the model are shown respectively. It is a figure which shows typically the distortion | strain of the primary molded object obtained by FEM structural analysis, (a) shows the case where distortion | strain is accept | permitted, respectively, (b) The case where distortion | strain is not accept | permitted, respectively.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  A composite molded body 1 shown in FIG. 1 is an exemplification of an embodiment of the present invention, and is formed by stacking a secondary molded body 3 on a primary molded body 2. The composite molded body 1 is used, for example, as a casing of an electronic device, and the primary molded body 2 is molded with a hard synthetic resin (for example, polycarbonate (PC)) to form an outer shell of the casing, and the secondary molded body 2 The molded body 3 is molded from a soft synthetic resin (for example, silicone rubber) and functions as a seal member. FIG. 1 shows a semi-conceptual configuration of the composite molded body 1 and does not show a specific shape suitable for a specific application (the same applies to FIG. 2 and subsequent figures).

  As shown in FIG. 2, the cross-sectional shape of the primary molded body 2 is substantially convex, and a core portion 5 is erected at the center of a horizontal skin plate 4. The skin plate 4 is a part constituting the outer shell of the housing. The core part 5 is a part that literally functions as a core of the seal member, and the secondary molded body 3 (the outline is indicated by a broken line in FIG. 2) is molded so as to surround the core part 5. The secondary molded body 3 is in contact with the primary molded body 2 in the range indicated by symbol A in the figure.

  In addition, a bank-like portion 6 is formed at the boundary of the range A and protrudes from the skin plate 4. In other words, the bank-like portion 6 is arranged on the boundary line that divides the portion overlapping the secondary molded body and the other portion in the planar shape of the primary molded body 2 (the shape seen from the direction B in FIG. 2). The The height of the bank-shaped portion 6 is such that the top end of the bank-shaped portion 6 comes into contact with the mold when the primary molded body 2 is inserted into the mold for molding the secondary molded body 3. At least you need. The procedure for determining the shape of the bank 6 will be described later.

  As shown in FIG. 3, the secondary molded body 3 is molded by inserting the primary molded body 2 between the lower mold 7 and the upper mold 8 and press-fitting the soft synthetic resin into the cavity 10 through the gate 9. And do it. At this time, since the bank-like part 6 is in contact with the inner surface of the upper mold 8, the soft synthetic resin press-fitted into the cavity 10 is blocked by the bank-like part 6 and does not leak out of the cavity 10. Therefore, generation | occurrence | production of a burr | flash is prevented. In addition, when using a silicone rubber for the soft synthetic resin of the raw material of the secondary molded body 3, LIM molding (Liquid Injection Molding) can be performed. That is, a secondary material 3 is formed by press-fitting a liquid material (a mixture of silicone rubber and a curing agent) into the cavity 10 with an injection molding machine. In addition, since the injection molding machine for LIM shaping | molding is known (for example, patent document 3), detailed description is abbreviate | omitted.

  As described above, the height of the bank-shaped part 6 is such that when the primary molded body 2 is inserted between the lower mold 7 and the upper mold 8, the top end of the bank-shaped part 6 is the upper mold 8. The height that makes contact with the inner surface is selected, but the height of the bank portion 6 is preferably deformed when it comes into contact with the inner surface of the upper mold 8. This is because the top end of the bank-like portion 6 is in close contact with the inner surface of the upper mold 8 to effectively prevent the leakage of the soft synthetic resin. Moreover, it is because the margin with respect to the shaping | molding precision of the primary molded object 2, and the deformation | transformation after shaping | molding is required. That is, even if there is an error in the size and shape of the primary molded body 2, a margin is required for the top end of the bank-shaped portion 6 to be in close contact with the inner surface of the upper mold 8. At this time, the area where the bank-shaped part 6 is deformed and the compressive fracture strain is generated remains in the cross section or the vicinity of the bank-shaped part 6 and does not reach the back side of the skin plate 4 (the surface in contact with the lower mold 7). desirable. It is because the external appearance of the composite molded body 1 is impaired when the range in which the compressive fracture strain occurs is wide.

In order to satisfy such requirements, the shape and dimensions of the bank 6 are specifically determined by the following procedure.
(Step 1) As shown in FIG. 4A, a height H and a width W of the bank 6 are assumed. The product thickness t of the primary molded body 2 is determined in advance, and is treated as a constant in the following procedure.
(Step 2) As shown in FIG. 4B, based on the clearance (design value) between the lower mold 7 and the upper mold 8, the height H1 after the deformation of the bank 6 is obtained and the deformation is determined. The shape and dimensions of the later bank-shaped portion 6 are estimated.
(Step 3) A crushing load F necessary for crushing the bank portion 6 from the height H to H1 is estimated. If the crushing load F is larger than the mold clamping force of the molding machine, that is, if the molding machine cannot generate the crushing load F, the process returns to step 1 and the height H and width W of the bank 6 And the height H1 after a deformation | transformation is changed.
(Step 4) As shown in FIG. 4C, an FEM (finite element method) structural analysis model 11 is created based on the shape and dimensions of the deformed primary molded body 2, and the lower side of the structural analysis model 11 (External surface of the primary molded body 2) is fixed, a crushing load F is applied to the upper side (the upper surface of the bank-like portion 6), and FEM structural analysis is performed.
(Step 5) As a result of the analysis, as shown in FIG. 5 (a), if the region where the compressive fracture strain occurs does not reach the lower side of the structural analysis model 11 (the external appearance surface of the primary molded body 2), The shape and size of the part 6 are determined to be appropriate. On the other hand, as shown in FIG. 5B, when the region where the compressive fracture strain reaches the lower side of the structural analysis model 11 (appearance surface of the primary molded body 2), the shape and dimensions of the bank-like portion 6 are not good. Since it is determined to be appropriate, the process returns to Step 1 to change the height H, width W, and height H1 after deformation of the bank 6.

The molding (manufacturing) of the composite molded body 1 is performed in the following steps.
(Structural analysis step) According to the above procedure, the FEM structural analysis is performed on the primary molded body 2 to determine the shape and dimensions of the bank-shaped portion 6.
(Primary forming step) The primary formed body 2 including the bank-like portion 6 whose shape and dimensions are determined in the previous step is formed.
(Secondary molding process) The primary molded body 2 molded in the previous process is placed on the lower mold 7, the upper mold 8 is placed on the primary molded body 2, and a soft synthetic resin is press-fitted into the cavity 10. The secondary molded body 5 is molded.

  In addition, in the said embodiment, although the housing | casing of the electronic device was illustrated as an application of the composite molded object 1, the application of the composite molded object of this invention is not limited to the housing | casing of an electronic device. It is not limited to a housing. The composite molded body has many uses, for example, as various types of apparatuses, housings, housings, and parts for industrial, consumer, and academic purposes. Further, the shape of the composite molded body is not limited to that shown in FIGS.

  Moreover, although polycarbonate (PC) was illustrated as a raw material of the primary molded object 2, the raw material of the primary molded object which concerns on this invention is not limited to polycarbonate (PC). Various materials can be selected according to the purpose and application. For example, polybutylene terephthalate (PBT), polyphenylene oxide (PPO), polyamide (PA), polyphthalamide (PPA) and the like can be selected.

  Moreover, although the silicone rubber was illustrated as a raw material of the secondary molded object 3 and the example which performs LIM molding of the secondary molded object 3 was shown, the raw material of the secondary molded object which concerns on this invention is not limited to silicone rubber. However, it is not limited to a soft synthetic resin. Moreover, the molding method of the secondary molded body 3 is not limited to LIM molding. Thermoplastic synthetic resins such as polyethylene thermoplastic resins and polyester thermoplastic resins may be heated and injection molded.

  Moreover, in the said embodiment, the example provided with the core part 5 was shown. By providing the core part 5, desired rigidity can be ensured while giving a desired height to the seal member. However, since the core part 5 is an optional component, the core part 5 can be omitted depending on the size and shape of the seal member.

  Moreover, the cross-sectional shape of the bank-shaped part 6 is not limited to the triangle as illustrated. For example, various shapes such as a rectangle, a trapezoid, or a semicircle can be selected.

  Moreover, in the said embodiment, although the structural analysis model 11 was created based on the shape and dimension of the primary molded object 2 after a deformation | transformation, and the FEM structural analysis was performed, the primary before a deformation | transformation was shown. The compact 2 (FIG. 4 (a)) may be modeled, and the crushing load F necessary for deformation to the shape shown in FIG. 4 (b) and the strain distribution after deformation may be obtained by FEM structural analysis. . The crushing load F and strain distribution can be estimated more accurately.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to the specific embodiment which concerns, This invention includes the invention described in the claim, and its equivalent range It is. Hereinafter, the invention described in the scope of claims of the present application will be appended.

(Appendix 1)
In a composite molded body in which a secondary molded body is formed by overlapping a secondary molded body on the primary molded body, the primary molded body is a bank-like shape that divides a portion that protrudes from the surface and overlaps with the secondary molded body and other portions. A composite molded body having a size and a shape that abuts against an inner surface of a mold for molding the secondary molded body.

(Appendix 2)
The bank-like part has a shape that does not reach the surface on the opposite side of the bank-like part in a range where compression fracture strain is generated by being pressed by the mold when the secondary compact is molded. The composite molded body according to Supplementary Note 1.

(Appendix 3)
The composite molded body according to appendix 1, wherein the secondary molded body forms a seal member.

(Appendix 4)
The supplementary note 3 is characterized in that the primary compact includes a core protruding from the surface of the primary compact, and the secondary compact surrounds the core to form a seal member. Composite molded body.

(Appendix 5)
The composite molded body according to appendix 1, wherein the secondary molded body is formed by liquid resin molding.

(Appendix 6)
The composite molded body according to appendix 5, wherein the secondary molded body is formed by liquid resin molding of silicone rubber.

(Appendix 7)
A step of forming a primary molded body provided with a bank-like portion that bulges from the surface and overlaps with the secondary molded body and a portion other than that, and a secondary molded body is formed on the bank-shaped portion of the primary molded body A method for forming a composite molded body, comprising: a step of molding a secondary molded body by bringing an inner surface of a metal mold into contact with and pressing.

(Appendix 8)
The FEM structural analysis is performed on the primary molded body, and the range in which the dam-like portion is pressed by the mold to cause compressive fracture strain does not reach the surface on the opposite side of the dam-like portion, The method for forming a composite molded body according to appendix 7, further comprising a step of determining the shape of the primary molded body.

DESCRIPTION OF SYMBOLS 1 ... Composite molded object, 2 ... Primary molded object, 3 ... Secondary molded object, 4 ... Leather plate, 5 core part, 6 ... Embankment part, 7 ... Lower metal mold, 8 ... Upper metal mold, 9 ... Gate 10 ... cavity, 11 ... structural analysis model

Claims (8)

In a composite molded body in which a secondary molded body is overlaid on a primary molded body,
The primary molded body includes a bank-shaped portion that bulges from the surface and overlaps the secondary molded body and the other portion.
The bank-shaped portion has a size and a shape that abuts against an inner surface of a mold for molding the secondary molded body. The bank-shaped part has a shape that does not reach the surface on the opposite side of the bank-shaped part in a range where compression fracture strain is generated by being pressed by the mold when the secondary molded body is molded. The composite molded body according to claim 1. The composite molded body according to claim 1, wherein the secondary molded body forms a seal member. The primary molded body includes a core portion protruding from the surface of the primary molded body,
The composite molded body according to claim 3, wherein the secondary molded body surrounds the core portion to form a seal member. The composite molded body according to claim 1, wherein the secondary molded body is formed by liquid resin molding. The composite molded body according to claim 5, wherein the secondary molded body is formed by liquid resin molding of silicone rubber. A step of forming a primary molded body provided with a bank-like portion that bulges from the surface and overlaps with the secondary molded body and the other portion;
A step of abutting and pressing an inner surface of a mold for forming a secondary molded body on the bank-shaped portion of the primary molded body to form a secondary molded body,
A method for forming a composite molded body. The FEM structural analysis is performed on the primary molded body, and the range in which the dam-like portion is pressed by the mold to cause compressive fracture strain does not reach the surface on the opposite side of the dam-like portion, Determining the shape of the primary molded body,
The method for forming a composite molded body according to claim 7, further comprising:

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