JP2017196863A - Compression molding method of fiber-reinforced resin molding, and die - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compression molding method of a fiber-reinforced resin molding which prevents exposure of a flow mark and a reinforced-fiber.SOLUTION: A compression molding method of a fiber-reinforced resin molding (14) includes: a material resin charging step of charging a material resin (13) being a molten resin containing a reinforced-fiber into a cavity (8) of dies (2 and 3); and a compression step of driving the dies (2 and 3) in a mold-closing direction and filling cavities (7 and 8) with the material resin (13). The material resin charging step includes: ejecting a plurality of rods (9) to the upper part of the cavity (8) of the die (3); mounting the material resin (13) on the plurality of rods (9); and thereby preventing contact of the material resin (13) and the surface of the cavity (8). The compression step includes: retracting the plurality of rods (9); mounting the material resin (13) on the surface of the cavity (8); and driving the dies (2 and 3) in the mold-closing direction.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a compression-molding method for a fiber-reinforced resin molded product, which molds a molded product from a so-called fiber-reinforced resin containing reinforcing fibers such as carbon fiber and glass fiber, and a mold.

  A molded product molded from a so-called fiber reinforced resin containing reinforcing fibers such as carbon fiber and glass fiber, that is, a fiber reinforced resin molded product has high strength while being lightweight. Therefore, the fiber reinforced resin molded product is used in various fields, and is often used in, for example, automobile parts. The under cover provided on the bottom surface of the automobile is also a fiber reinforced resin molded product, which is relatively large but has sufficient strength so that it is formed thin and lightweight.

  The fiber reinforced resin molded product can be molded by various molding methods. For example, the fiber reinforced resin can be molded by injection molding in which a fiber reinforced resin is injected into a clamped mold to obtain a molded product. However, when molding a relatively thin molded product, so-called press molding, that is, compression molding, is advantageous. In compression molding, a pair of molds are opened, a fiber-reinforced resin in a molten state is introduced into the molds, and the pair of molds is tightened. When the mold is opened after cooling and solidifying the fiber reinforced resin, a fiber reinforced resin molded product shaped into a desired shape is obtained.

JP-A-5-131456

  When a fiber-reinforced resin molded product is obtained by compression molding, a molten resin containing reinforcing fibers is put into the mold, but the resin loses its fluidity because the part in contact with the mold cavity is rapidly cooled. Therefore, the fiber reinforced resin molded product obtained after compression molding is liable to cause a problem in quality because a flow mark is formed or the reinforcing fiber is exposed on the surface. Patent Document 1 describes a mold that can prevent the formation of flow marks and the exposure of reinforcing fibers. A mold 50 described in Patent Document 1 is a compression mold, and includes an upper mold 51 and a lower mold 52 as shown in FIG. A forming protrusion 54 is formed on the lower mold 52, a steel plate 56 is fixed on the forming protrusion 54, and a coating 58 having a heat insulating property is formed on the surface of the steel plate 56. The coating 58 is made of a resin having a thermal deformation temperature higher by 10 ° C. or more and a lower thermal conductivity than the resin to be compression-molded, and is made of, for example, polyethylene terephthalate. A recess 59 is formed in the upper mold 51, and a compression molding cavity is constituted by the coating 58 of the lower mold 52 and the recess 59 of the upper mold 51. In this mold 50, the mold 50 is opened, a sheet-like molten resin 61 of material is placed on the upper mold 52, and the mold 50 is tightened. That is, the upper mold 51 is pressed against the lower mold 52. Then, the molten resin 61 is compressed by the cavity, and when the mold 50 is opened after cooling and solidification, a molded product having a desired shape is obtained. By the way, since the sheet-like molten resin 61 placed on the upper mold 52 is placed on the coating 58 having a low thermal conductivity, it is not rapidly cooled and the fluidity is not lowered. Accordingly, a flow mark is not formed on a molded product obtained by compression molding. By the way, the mold 50 is also suitable for compression molding of fiber reinforced resin, and no flow mark is formed even when a molten resin containing reinforcing fiber is molded, and the reinforcing fiber is exposed on the surface of the molded product to be molded. I don't have to.

  Since the metal mold 50 described in Patent Document 1 is provided with a coating 58 having heat insulation properties, rapid cooling of the molten resin can be prevented, and thus a molded product is obtained from the fiber reinforced resin by compression molding. In some cases, a flow mark is not formed or the reinforcing fiber is not exposed on the surface of the molded product, and a molded product with high quality can be molded. That is, it is excellent because a fiber-reinforced resin molded product with high quality can be obtained. However, there are some problems to be solved. First, the durability problem of the film 58 can be raised. Since the coating 58 is made of a resin such as polyethylene terephthalate, it can be said that the coating 58 is relatively durable. However, when the molding is repeatedly performed, the coating 58 is worn or deteriorated. Alternatively, heating and cooling are repeated for each molding, but this frequently causes expansion and contraction due to thermal expansion. If it does so, the film 58 will peel from the steel plate 56. FIG. When the coating is worn, deteriorated or peeled in this way, the heat insulating property cannot be maintained, and a high-quality fiber-reinforced resin molded product cannot be obtained. Next, the problem of productivity reduction can be raised. In the mold 50 described in Patent Document 1, in order to mold a high-quality fiber-reinforced resin molded product, the coating 58 needs to have sufficient heat insulation. Then, the coating film 58 needs to be formed from a predetermined film thickness. However, if the heat insulating property is sufficiently increased, the cooling efficiency is lowered. That is, it takes time to cool the resin after compressing the molten resin 61 of the material. If it does so, a shaping | molding cycle will become long and a shaping | molding cost will become large.

  The present invention aims to solve such problems. Specifically, when molding a molded product from a fiber reinforced resin, the flow mark is not formed on the molded product or the reinforcing fiber is not exposed, It is an object of the present invention to provide a compression-molding method for a fiber-reinforced resin molded product with high productivity and a mold used for the compression-molding method without causing the mold to wear or deteriorate even after repeated molding. .

  In order to achieve the above object, the present invention is configured as a compression molding method for a fiber reinforced resin molded product. The compression molding method includes a material resin charging step in which a material resin, which is a molten resin containing reinforcing fibers, is injected into a mold cavity, and a fiber is formed by driving the mold in the mold closing direction and filling the cavity with the material resin. And a compression process for forming a reinforced resin molded product. In the present invention, the material resin charging step projects a plurality of rods in advance above the cavity of the mold and places the material resin on the plurality of rods, thereby inhibiting the contact between the material resin and the surface of the cavity. Like that. In the compression step, the plurality of rods are retracted so that the material resin is placed on the surface of the cavity, and the mold is driven in the mold closing direction.

That is, the invention according to claim 1 of the present invention includes a material resin charging step of charging a material resin, which is a molten resin containing reinforcing fibers, into a cavity of a mold that has been opened, and driving the mold in the mold closing direction. Then, in the compression molding method of a fiber reinforced fiber molded article comprising a compression step of molding the fiber reinforced resin molded article by filling the cavity with the material resin, the material resin charging step is performed in advance in the mold. A plurality of rods are protruded above the cavity, and the material resin is placed on the plurality of rods, thereby preventing contact between the material resin and the surface of the cavity. Fiber reinforced, wherein a plurality of rods are retracted so that the material resin is placed on the surface of the cavity, and the mold is driven in a mold closing direction. Configured as a compression molding method of fat moldings.
According to a second aspect of the present invention, in the compression molding method according to the first aspect, the material resin is formed into a sheet shape and charged into the cavity in the material resin charging step. It is configured as a compression molding method for fiber reinforced resin molded products.
According to a third aspect of the present invention, in the compression molding method according to the first or second aspect, the material resin charging step causes the plurality of rods to protrude from the surface of the cavity and the plurality of the material resins. It is configured as a compression molding method of a fiber reinforced resin molded product characterized by being placed on the tip of the rod.
According to a fourth aspect of the present invention, in the compression molding method according to the first or second aspect, in the material resin charging step, the plurality of rods are protruded from the side of the mold and the material resin is injected. It is configured as a compression molding method of a fiber reinforced resin molded product characterized by being placed on the side surface of the plurality of rods.
The invention according to claim 5 is a compression molding die for obtaining a fiber reinforced resin molded product by compression molding a material resin which is a molten resin containing reinforcing fibers, and the die is protruded so as to freely advance and retract. When a material resin, which is a molten resin containing reinforcing fibers, is provided in the cavity of the mold with a plurality of rods, the plurality of rods are introduced in a state protruding in advance above the cavity, Accordingly, the material resin is prevented from coming into contact with the surface of the cavity, and when the mold is compressed, the rod is retracted and the material resin is placed on the cavity. It is comprised as a metal mold | die for compression molding of the fiber reinforced resin molded product characterized by having.
A sixth aspect of the present invention is the compression molding die according to the fifth aspect, wherein the plurality of rods are protruded from the surface of the cavity so as to freely advance and retract. It is comprised as a metal mold for compression molding of a fiber reinforced resin molded product.
A seventh aspect of the present invention is the compression molding mold according to the fifth aspect, wherein the plurality of rods are protruded from the side of the mold so as to freely advance and retract. It is comprised as a metal mold | die for compression molding of the fiber reinforced resin molded product characterized by these.

  As described above, the present invention includes a material resin charging process in which a material resin, which is a molten resin containing reinforcing fibers, is injected into a cavity of a mold that has been opened, and a mold is driven in the mold closing direction into the cavity. The present invention is directed to a compression molding method for a fiber reinforced fiber molded article comprising a compression step of forming a fiber reinforced resin molded article by filling a material resin. According to the present invention, in the material resin charging step, a plurality of rods are previously projected above the cavity of the mold, and the material resin is placed on the plurality of rods, thereby making contact between the material resin and the surface of the cavity. It is configured to inhibit. When the material resin comes into contact with the surface of the cavity, it rapidly cools and loses fluidity. However, according to the present invention, the material resin does not contact the surface of the cavity. That is, since the material resin is placed on the rod, an air layer having high heat insulation is interposed between the material resin and the cavity surface. This prevents rapid cooling of the material resin and maintains fluidity. According to the present invention, the compression step retracts the plurality of rods so that the material resin is placed on the surface of the cavity, and the mold is driven in the mold closing direction. The material resin is compressed and filled in the entire cavity without interfering with the compression process. In other words, according to the present invention, since the material resin is filled in the cavity in a state where the fluidity is maintained, the obtained fiber reinforced resin molded product has no flow mark formed, and the reinforcing fiber is exposed on the surface. Nor. That is, a high-quality fiber-reinforced resin molded product can be molded. The plurality of rods have high durability if they are made of metal, and there is no problem of wear or deterioration even if the fiber-reinforced resin molded product is repeatedly formed. In the compression process, the material resin comes into contact with the surface of the cavity and is quickly cooled. That is, since the cooling efficiency is high, the molding cycle of the fiber-reinforced resin molded product can be shortened, and the production cost can be reduced. According to another invention, in the material resin charging step, the material resin is formed in a sheet shape and is charged into the cavity. Since it forms in a sheet form, material resin can be thrown in so that material resin may cover the whole cavity. If it does so, in the compression process implemented after that, the quantity which material resin will flow can be made small. This reliably prevents the formation of flow marks and the exposure of reinforcing fibers.

It is front sectional drawing which shows the metal mold | die for compression molding of the fiber reinforced resin molded product concerning the 1st Embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows typically the compression molding method of the fiber reinforced resin molded product which concerns on embodiment of this invention, The (a)-(e) concerns on 1st Embodiment of this embodiment in each process of a compression molding method. It is front sectional drawing which shows the metal mold | die for compression molding. It is front sectional drawing which shows the metal mold | die for compression molding of the fiber reinforced resin molded product concerning the 1st Embodiment of this invention in the state in which material resin was supplied. It is a figure which shows the metal mold | die for compression molding of the fiber reinforced resin molded product which concerns on the 2nd Embodiment of this invention, The (a) is front sectional drawing, The (a) is a top view of a lower metal mold | die. It is front sectional drawing which shows the metal mold | die for compression molding which concerns on the 2nd form of this Embodiment in each process of the compression molding method of the fiber reinforced resin molded product which concerns on embodiment of this invention. It is front sectional drawing which shows the metal mold | die for compression molding of a prior art example.

  Embodiments of the present invention will be described. The compression molding die 1 according to the first embodiment of the present invention is a die for molding a fiber reinforced resin molded product made of a resin containing a reinforced fiber, that is, a fiber reinforced resin, by a compression molding method. As shown in FIG. 1, the compression mold 1 is composed of an upper mold 2 and a lower mold 3, and the mold is opened by a press machine not shown in the drawing or in the mold closing direction. It is designed to be driven. A convex portion 5 is formed at the center of the upper mold 2. The lower mold 3 has a recess 6 at the center so as to correspond to the protrusion 5. The convex portion 5 and the concave portion 6 constitute a cavity for molding a fiber reinforced resin molded product. That is, the surfaces of the protrusions 5 and the recesses 6 are the cavity surfaces 7 and 8.

  In the compression mold 1, the lower mold 3 is provided with a structure unique to the present invention. In other words, a plurality of rods 9, 9,... In this embodiment, the rods 9, 9,... Are formed in a cylindrical shape having a predetermined diameter, and are inserted into holes that are opened in the cavity surface 8 of the lower mold 3. The lower ends of the rods 9, 9,... Reach the space in the lower mold 3, and are fixed to the plate 11 accommodated in the space. When the plate 11 is driven upward, the rods 9, 9,... Protrude from the cavity surface 8, and when driven downward, the rods 9, 9,. In the retracted state, the tip surfaces, that is, the upper surfaces of the rods 9, 9,... Are smoothly connected to the cavity surface 8. At this time, the upper surfaces of the rods 9, 9,... Constitute a part of the cavity surface 8. In the present embodiment, the lengths of the plurality of rods 9, 9,... Are not uniform. As shown in FIG. 1, the central portion of the recess 6, that is, the central portion of the cavity surface 8 is slightly raised as compared to the periphery. The lengths of the rods 9, 9, etc. provided at the raised positions are selected according to the degree of the swells, and when the rods 9, 9,. The upper surfaces of the rods 9, 9,... Are smoothly continuous with the cavity surface 8.

  A method for molding a fiber-reinforced resin molded product using the compression molding die 1 according to the present embodiment will be described. First, the material of the molded product will be described. The material is a so-called fiber reinforced resin containing a reinforced fiber whose base material is a thermoplastic resin, that is, a composite material. In this embodiment, for example, a fiber reinforced resin made of a polyamide synthetic resin containing carbon fiber is used. ing. In the compression molding method according to the present embodiment, a fiber reinforced resin as a material is melted and extruded from a T die by a plunger injection device, a continuous plasticizing injection device, or the like. The molten fiber reinforced resin extruded from the T-die is formed into a sheet shape, and this sheet-like fiber reinforced resin is used as a material resin that is a material for compression molding. In the case of a resin that does not contain reinforcing fibers, the fluidity is high when in a molten state, but in the case of fiber reinforced resins that contain reinforcing fibers, the fluidity is maintained even if the base resin is in a molten state. Is relatively small. Therefore, since the material resin contains reinforcing fibers, the fluidity is small enough to maintain the sheet-like shape and transport it to the compression mold 1 even in a molten state.

First, a material resin charging step is performed. That is, as shown in FIG. 2A, the compression molding die 1 is opened and the plate 11 is driven so that a plurality of rods 9, 9... Are removed from the cavity surface 8 of the lower die 3. .. So that the upper surfaces of the rods 9, 9,... Are located above the cavities. A sheet-like material resin 13 is put into the cavity of the lower mold 3. Then, as shown in FIG. 2A, the material resin 13 covers substantially the entire concave portion 6, that is, substantially the entire cavity surface 8, but is supported by the tips of the rods 9, 9,. Become. Thereby, as shown enlarged in FIG. 3, the rod 9, 9 material resin 13 projecting from the cavity surface 8 of the lower die 3, only ... height, i.e. the floating state by l ₂ Become. That height so that the thermal insulation is high air layer l ₂ is formed between the resin material 13 and the cavity surface 8. As a result, the material resin 13 is not cooled and maintained without loss of fluidity.

  Following the material resin charging step, a compression step is performed. That is, as shown in FIG. 2C, the plate 11 is driven to retract the rods 9, 9,. Then, the upper surfaces of the rods 9, 9,... Constitute a part of the cavity surface 8, and the material resin 13 contacts the cavity surface 8 as a whole. Simultaneously with the contact, cooling of the material resin 13 in contact with the cavity surface 8 starts, but while the fluidity of the material resin 13 is ensured, as shown in FIG. Is driven in the mold closing direction. Then, the material resin 13 is compressed and filled into the cavity. The molten material resin 13 has a high fluidity and smoothly flows along the cavity surfaces 7 and 8, and a fiber-reinforced resin molded article 14 having excellent transferability is formed. In the compression step, the rods 9, 9,... May be retracted and the upper mold 2 may be driven simultaneously. If it is carried out at the same time, the problem of lowering of fluidity due to cooling of the material resin 13 hardly occurs. After the compression step, after waiting for cooling and solidification, the compression mold 1 is opened as shown in FIG. At this time, the plate 11 may be driven to project the plurality of rods 9, 9,... Like a molded product ejection rod. In this way, a high-quality fiber-reinforced resin molded product 14 is obtained. Thereafter, molding is performed in the same manner.

The material resin 13 is quickly cooled when it comes into contact with the cavity surface 8. However, if the air layer is secured between the material resin 13 and the cavity surface 8 by being supported by the rods 9, 9,. Is done. This is apparent when considering the amount of heat per unit time flowing from the material resin 13 to the cavity surface 8 of the lower mold 3, that is, the heat flux. As shown in FIG. 3, the thickness of the material resin 13 is l _1, T ₁ the temperature of the material resin _13, the thermal conductivity of the material resin 13 and lambda _1, Tara if there is no air layer, that When the material resin 13 is not resting directly on the cavity surface 8 of the mold temperature T _K, the heat flux q _a flowing material resin 13 in the lower mold 3 is given as one set. On the other hand, as shown in FIG. 3, if an air layer having a height l ₂ and a thermal conductivity of λ ₂ is secured by the rods 9, 9,. heat flux q _b flowing in is given as equation (2).

The thermal conductivity λ ₁ of the material resin 13 is 0.2 to 0.3 W / m · K, whereas the thermal conductivity λ ₂ of dry air is as extremely small as 0.0241 W / m · K. . Therefore, the heat flux clearly becomes q _a >> q _b from the first and second formulas. Then, the material resin 13 supported by the rods 9, 9,... Is hard to take away from the lower mold 3 and is difficult to cool. That is, it turns out that fluidity is not lost.

  Next, a compression molding die 1 'according to a second embodiment of the present invention will be described. The compression molding die 1 ′ according to the second embodiment of the present invention is configured as shown in FIG. 4, but is similar to the compression molding die 1 according to the previous embodiment. About the member, the same code | symbol is attached | subjected and description is abbreviate | omitted. The compression molding die 1 ′ is characterized in that a plurality of rods 9 ′, 9 ′,... Are provided in the lower die 3 ′ so as to protrude forward and backward from the side. That is, the plurality of rods 9 ′, 9 ′,... Protrude from the left and right sides of the lower mold 3 ′ toward the center so as to be positioned above the cavity surface 8. When the material resin charging step is performed in the compression molding die 1 ′ according to this embodiment, as shown in FIG. 5A, the material resin 13 is composed of a plurality of rods 9 ′, 9 ′. , ... will be supported on the belly, that is, on the side. The material resin 13 is prevented from contacting the cavity surface 8. In the compression step, the plurality of rods 9 ′, 9 ′,... Are retracted as shown in FIG. 5 (a) so that the material resin 13 is placed on the cavity surface 8, and the upper mold 2 Is driven in the mold closing direction. The fiber reinforced resin molded product 14 is molded as in the previous embodiment.

  The compression-molding dies 1, 1 'according to the present embodiment can be variously modified. For example, in this specification, the rods 9, 9,..., The rods 9 ′, 9 ′,... Are expressed as “rods” reminiscent of a large-diameter rod-shaped member, but the diameter, that is, the thickness is arbitrarily selected. be able to. In other words, the “pin” may be composed of a suitable small-diameter rod-shaped member, and in this specification, the member capable of supporting the material resin 13 is represented as a “rod” regardless of the diameter. Yes. This is because it is not necessary to stick to the size of the diameter if the contact between the material resin 13 and the cavity surface 8 of the lower mold 3 is inhibited in the material resin charging step. Further, the rods 9, 9,... Have been described as being cylindrical, but may be formed in a prismatic shape such as a triangular prism or a quadrangular prism. Furthermore, you may be comprised from the other shape. Furthermore, the rods 9, 9,... Do not have to have a constant diameter in the axial direction. For example, the upper end portion may have a large diameter and become narrower downward. In the case of the compression molding die 1 according to the first embodiment, the rods 9, 9,... Can protrude from the cavity surface 8, and the upper surfaces of the rods 9, 9,. If the surface 8 is configured, there is no problem, and in the case of the compression molding die 1 'according to the second embodiment, the rods 9', 9 ', ... are positioned above the cavity. This is because there is no problem as long as it can freely move forward and backward, and these shapes do not matter. Further, the rods 9, 9 ′,. In the first embodiment, the rods 9, 9,... Are projected vertically, and in the second embodiment, the rods 9 ', 9',. It is also possible and the protruding direction can be arbitrary.

  By the way, in the description of the compression molding method according to the present embodiment, it is described that the material resin 13 is not in contact with the cavity surface 8 in the material resin charging step. That is, it is described that the contact is completely inhibited by the rods 9, 9 ',. However, part of the material resin 13 may come into contact with the cavity surface 8 as long as the contact is substantially inhibited. This is because if the contact range is small, the whole is not cooled and the fluidity is not lost. Also, if the resin hardly flows in the subsequent compression step, the influence is small even if the material resin 13 comes into contact with the cavity surface 8 in the material resin charging step and the fluidity is lowered by cooling.

DESCRIPTION OF SYMBOLS 1 Mold for compression molding 2 Upper mold 3 Lower mold 5 Convex part 6 Concave part 7 Cavity surface 8 Cavity surface 9 Rod 11 Plate 13 Material resin 14 Fiber reinforced resin molded product

Claims (7)

A material resin charging step of charging a material resin, which is a molten resin containing reinforcing fibers, into the cavity of the mold that has been opened, and driving the mold in the mold closing direction to fill the cavity with the material resin. In a compression molding method of a fiber reinforced fiber molded article comprising a compression step of molding a fiber reinforced resin molded article,
In the material resin charging step, a plurality of rods are previously protruded above the cavity of the mold, and the material resin is placed on the plurality of rods, thereby forming the surface of the material resin and the cavity. To prevent contact,
The compression step includes retracting the plurality of rods so that the material resin is placed on the surface of the cavity, and driving the mold in a mold closing direction. Compression molding method for resin molded products.   2. The compression molding method according to claim 1, wherein the material resin is formed into a sheet shape and charged into the cavity in the material resin charging step. . 3. The compression molding method according to claim 1, wherein in the material resin charging step, the plurality of rods are protruded from the surface of the cavity, and the material resin is placed on tips of the plurality of rods. A method for compression molding a fiber-reinforced resin molded product. 3. The compression molding method according to claim 1, wherein in the material resin charging step, the plurality of rods are protruded from a side of the mold, and the material resin is placed on a side surface of the plurality of rods. A method for compression-molding a fiber-reinforced resin molded product. A compression molding mold for obtaining a fiber reinforced resin molded product by compression molding a material resin which is a molten resin containing reinforcing fibers,
The mold includes a plurality of rods protruding so as to freely advance and retract, and when a material resin that is a molten resin containing reinforcing fibers is put into the cavity of the mold, the plurality of rods are located above the cavity. In this state, the material resin is prevented from coming into contact with the surface of the cavity, and the rod is retracted when the mold is compressed. A mold for compression molding of a fiber-reinforced resin molded product, characterized in that is placed in the cavity. 6. The compression-molding mold according to claim 5, wherein the plurality of rods are protruded from the surface of the cavity so as to freely advance and retract. Mold for molding. 6. The compression-molding mold according to claim 5, wherein the plurality of rods are protruded from a side of the mold so as to freely advance and retract. Mold for compression molding.

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