JP2018134807A - Simulation method of resin fluidity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To predict how a resin is filled inside a mold simply and highly accurately by simulation.SOLUTION: A simulated container provided with a cavity part along a shape of an entire or a part of a resin molded product to be molded is prepared and an analysis material made of a resin or a soft material used for molding is filled in the cavity part of the simulated container, and the analysis material is compressed in the container to mold an analytical molded product. By inspecting and evaluating a strength or cross section state of the analytical molded product, a flow behavior of the resin at the time of actual molding is analyzed, and an analysis result is reflected in a product design.SELECTED DRAWING: Figure 7

Description

  In the present invention, in the case where a resin material to which FRP mixed with fibers and other fillers are added is poured into a mold and then cooled and solidified to form a resin product, the fluidity of the resin in the mold is previously determined. It relates to methods for predicting and verifying.

FRP (fiber reinforced resin) such as GFRP and CFRP exhibits characteristics such as high strength and high elastic modulus that are not found in a single resin by kneading fibers into the resin.
FRP is used as a material of a member that is lightweight and requires high strength, and an automotive interior / exterior material that is required to be lightweight and highly rigid is a surface of an FRP molded product 100 as shown in FIG. In many cases, a complicated uneven shape such as a rib 100a or a boss 100b is formed.

  In this case, if the uneven portions such as ribs and bosses are not sufficiently filled with fibers, the intended strength is not exhibited, resulting in product defects. In order to design strength with high accuracy, it is important to grasp that the uneven parts such as ribs and bosses are sufficiently filled with fibers, and it is usually necessary to design a mold for resin products having uneven parts. The behavior of the molten resin inside the mold is predicted using simulation software, and it is confirmed whether or not the resin is satisfactorily filled in the uneven portion (for example, see Patent Document 1).

JP 2014-226871 A

Although the simulation software can simulate a single resin with no filler mixed with high accuracy, in the simulation of FRP products, the calculation processing becomes complicated due to the fact that the observation target is a fine fiber, and the simulation is performed with high accuracy. Was insufficient to do.
As described above, it is very important to predict the filling property of the fibers in the fine uneven portions of the FRP product so as not to cause the product defect. Prior to commercialization of the FRP product, the mold is actually used. Thus, if the FRP molded product can be prototyped and evaluated, it is possible to surely confirm the degree of filling of the resin and fibers into the fine irregularities. However, for that purpose, it is necessary to produce an expensive mold, and it is not efficient from the viewpoint of time and cost required to repeatedly perform trial manufacture and evaluation.

  In predicting the fiber filling properties of FRP products, it is desired that the evaluation can be easily performed and the prediction accuracy is high, but there is no established method for satisfying these conditions.

  In view of such problems of the prior art, the present invention can easily and accurately predict how a resin is filled in a molding die by molding a resin molded product by a compression molding method. Thus, it is an object to shorten the design time of the resin molded product, thereby reducing the time and cost required for development.

As described above, it is inevitable that time and cost will be increased if a mold is actually produced and a resin molded product is made and evaluated using this mold.
Therefore, in solving the above problems, the present invention uses a simulated container as an alternative to an actual mold, actually uses an actual material or a material corresponding thereto, and fills the simulated container with this to perform molding. Thus, a method was constructed that can easily and accurately predict how the resin is filled into the mold.

That is, the resin fluidity simulation method of the present invention is a method for analyzing the flow behavior of the resin inside a molding die when molding a resin molded product by a compression molding method,
Produce a simulated container with a cavity along the shape of the whole or part of the resin molded product to be molded,
Filling the cavity of the simulated container with the analytical material made of resin or soft material used for the molding, and molding the molded article for analysis by compressing in the simulated container,
The flow behavior of the resin during actual molding of the resin molded product is analyzed by verifying and evaluating the strength or cross-sectional state of the molded product for analysis.

  In the simulation method of the present invention, the simulated container is filled in the cavity portion along the entire shape of the resin molded product to be molded, or a cavity portion along the shape of a part including the uneven portion of the resin molded product, and the cavity portion. The analysis material is configured to have a portion for compressing.

When the analytical material filled in the cavity is compressed at the compression site, if the simulated container is deformed by the reaction force generated from the material, the intended molded product cannot be obtained. In general molding, it is desirable to perform compression molding using a simulated container made of steel so that the shape as designed can be maintained.
Moreover, in order to suppress the deformation | transformation which arises at the time of compression molding, it is preferable that the simulation container is thick. To prevent deformation of the simulated container, the outer peripheral surface of the container may be reinforced by surrounding it with a metal plate or fiber reinforced resin, or reinforced by placing a metal plate or fiber reinforced resin inside the container. May be.

In the present invention, a simulated container formed of a synthetic resin or other material can be used in addition to the metal simulated container.
For example, by transferring the shape from a base simulated container to a material such as silicon, gypsum, or resin, a child container can be created by inverting the simulated mold. A grandchild-shaped container can be made by transferring the shape to. The material for analysis may be compression-molded using a mock-type transcript and a mold container made from the transcript series.

Furthermore, what was modeled with 3D printer as a synthetic resin simulation container can be used.
The 3D printer reads the shape drawn by 3D CAD, and repeats the lamination of the resin by, for example, the resin melting method according to the read shape to obtain the product shape. At that time, the lamination pitch and the void ratio inside the molded product Can be set.

  The simulated container produced by the 3D printer may be formed by any method such as a hot melt lamination method, an ink jet method, a powder sintering method, an optical modeling method, or a projection method. May be coated to smooth the surface or may be subjected to a release treatment so that the molded product can be easily removed from the container.

The simulated container modeled by the 3D printer evaluates how the resin and filler added to the concave and convex portions such as ribs and bosses formed on the surface of the target resin molded product enter. As long as it is possible, it may be in the form of molding the entire resin molded product, or may be molded in part.
As described above, in general, 3D printers can set the internal cavity ratio to shorten the molding time and material without changing the appearance, but in the present invention, the resin material is compressed with a simulated container. From the viewpoint of molding, it is not preferable that the rigidity is lowered due to the high void ratio inside the simulated container.
It is indispensable to create a 3D CAD model by actual product design, analyze the rigidity and strength of the product by CAE (Computer Aided Engineering), and verify the safety and lightness, but the shape data required for 3D printers Is also a 3D CAD model, and the use of a simulated container modeled by a 3D printer for simulation of resin fluidity is that it is not necessary to create a new 3D CAD model when preparing a container necessary for molding for predicting fillability This is a merit. By using a simulated container produced by a 3D printer for the simulation of resin fluidity, an extra process is omitted from the relationship in which 3D CAD is created in the process of obtaining the final product shape.

  As the material of the simulated container, a thermoplastic resin such as an ABS resin, a PLA resin, a polycarbonate resin, an ASA resin, or a polyetherimide resin, which is a material of the 3D printer, or a UV curable resin can be used. Among these resins, polycarbonate resins and polyetherimide resins having a high load deflection temperature and a high glass transition point are preferable.

  The glass transition temperature Tg of the synthetic resin constituting the simulated container is preferably 100 ° C. or higher, more preferably 140 ° C. or higher, and further preferably 160 ° C. or higher. By setting the glass transition temperature Tg in the above range, the rigidity of the simulated container can be further suppressed from being deformed due to temperature change, and deformation of the simulated container can be more accurately predicted.

  Further, when the simulated container is formed of a synthetic resin material, if the whole or a part thereof is provided transparent or translucent, it is possible to visually check the flow of the resin filled in the cavity from the outside of the container. This is preferable. In addition, the definition of translucent means that it has translucency so that the shadow of the filling material in the container can be confirmed from the outside by irradiating visible light from a light source such as an LED lamp.

As described above, simulation of resin fluidity is possible even using a synthetic resin-made simulated container, and the container can be filled with a filler-containing resin as an analysis material and compression molded.
For example, although a sheet molding compound material called SMC is filled with fibers, it is so soft that it can be bent by a human hand at room temperature after the material is produced, and curing progresses as a crosslinking reaction proceeds at a high temperature. Moreover, since it is arrange | positioned at a normal temperature at the time of a shaping | molding start, SMC material is a soft state.
When SMC material is used as a material for analysis, when performing compression molding using a simulated container, in order to compress and mold a soft resin in the molding process, the simulated container does not require an elastic modulus as high as that of a metal. Even in the manufactured simulated container, it is possible to transfer the shape of the resin molded product shaped on the inner surface of the cavity to the filling material and maintain the shape of the molded product.

The simulated container can be composed of a fixed mold having a hollow portion shaped along the whole or a part of the resin molded product to be molded, and a movable mold having a portion for compressing the analytical material filled in the hollow portion. . Both the fixed mold and the movable mold can be divided into a plurality of members and connected and integrated, and the fixed mold and the movable mold are clamped via fixing members such as bolts and nuts. Thus, the material filled in the movable mold can be configured to be compressed.
For example, a nut can be insert-molded in at least one mold of the simulated container, fastened with at least one mold and a bolt, and the movable mold can be press-connected to the fixed mold. In this case, it is preferable because a device for closing the mold is not required in the step of filling the material into the fixed mold. In addition, you may form so that it may fasten with a volt | bolt by making a hole smaller than a bolt diameter without insert-molding a nut.

  In the simulation method of the present invention, the analysis material can be a resin used for molding an actual resin molded product or a soft material having the same properties.

The resin used as the analysis material may be a thermosetting resin as described above, or may be a thermoplastic resin. However, when molding a thermoplastic resin, it is necessary to prepare a separate heat source and perform molding under a temperature condition that provides sufficient fluidity.
Even if it is a thermosetting resin, there is no problem if a separate heat source is prepared and the temperature is adjusted and then molded.

  When molding with a simulated container, it is possible to perform molding by adjusting the temperature of the simulated container in the same manner as with a normal molding die. In this case, the adjustment temperature is preferably lower than the glass transition temperature Tg of the analysis material from the viewpoint of formability.

Specifically, the glass transition temperature Tg (° C.) of the synthetic resin constituting the simulated container and the maximum temperature Tmax (° C.) during compression molding of the resin used as the analysis material are adjusted to satisfy the following formula (1). Can be.
Formula (1): −100 (° C.) ≦ T1-Tmax ≦ 300 (° C.)
More specifically, the lower limit of the numerical value obtained from the formula (1) is preferably −100 ° C. or higher, more preferably −50 ° C. or higher, and further preferably −30 ° C. or higher.
The upper limit of the numerical value obtained from the formula (1) is not particularly specified, but is preferably 300 ° C. or lower, more preferably 100 ° C. or lower, and further preferably 50 ° C. or lower. It is particularly preferable that the temperature is 0 ° C. or lower. By setting the numerical value obtained from Equation (1) within the above range, the simulation of the molding material can be predicted more accurately without the simulated container being deformed for the purpose of obtaining the resin molded product in a desired shape.

  In addition, when SMC material is used as an analysis material, a sheet-like material made by impregnating fibers with resin is filled into the cavity of a simulated container provided along the shape of the molded product, and analyzed by compression molding. A molded product can be obtained. Since molding of SMC material can be performed with a material kept at room temperature or low temperature, the material filled at room temperature may be compressed and then heated without adjusting the temperature of the simulated container. Is possible.

The fibers or fillers contained in the analytical material to be filled in the simulated container may be arranged randomly at the start of filling the container or may be arranged with regularity.
There is no limitation on the number of fibers or fillers mixed in the resin, and at least one fiber or filler is mixed, but it is preferable that the filling rate is such that the fluidity of the resin during compression molding is hindered. Absent.
The length of the fiber is short and is preferably 1 mm or more. The length is not limited, but the longest linear distance in the shape of the molded article as the base material is preferably set as the upper limit. For example, when a 25 mm square substrate is used, the upper limit is about 35 mm when there are fibers on the diagonal.

  Even if the material filled in the simulated container does not contain fibers, it is possible to evaluate only the fluidity of the resin. For example, by filling a colored material into a container, it is possible to know from which part of the analysis molded product taken out from the container which resin is originally placed in a specific part.

When the fiber-containing resin is compression-molded in the simulated container, the fiber-containing resin may be compressed by a press used in normal molding, or a mold may be clamped with a vise.
In addition, when the simulated container includes a fixing mechanism such as fastening a bolt, the material filled in the container cavity can be pressed and compressed into the container by the force of bolt fastening.

  Molding with a simulated container can be confirmed in the middle of the molding state by stopping the mold without completely closing the mold. It is also possible to make the behavior at the time of filling failure called short shot appear.

As an evaluation of the molded article for analysis molded by the simulated container, a method for checking how the fibers are distributed by baking the molded article, a method for measuring the mechanical properties by cutting the molded article, Or it can evaluate by taking the method of confirming a fiber by X-ray imaging. Since the required characteristics differ depending on the target resin molded product, any method for evaluating the molded product may be used.
At this time, the analysis molded product can be evaluated by, for example, cutting the entire simulated container or confirming it by baking without removing it from the simulated container.

  After evaluating the moldability using the analytical molded product and confirming that the target shape is sufficiently filled with fibers, the resin molded product that reflects the moldability predicted by the simulated container It is possible to produce a mold for use and produce a product using the mold.

By performing the resin flow test using the produced simulated container in the above steps, it becomes possible to predict the moldability and performance of a resin molded product in an arbitrary shape having an uneven surface on the surface.
If the prediction result is sufficient with respect to the target value, it is possible to reflect the result in the mold for actually producing the product when designing the product. It is possible to make a simulated container by using a printer or perform a simulation of resin fluidity in which molding conditions are corrected, and search for conditions and shapes that satisfy the target value.
If it is sufficiently possible to make a product with a simulated container, it may be used for production as it is.

It is the figure which showed an example of the form of the resin molded product to which this invention is applied. It is the member expansion | deployment external view of the simulation container which shape | molds the resin molded product of FIG. (A) to (C) is a diagram showing a process of constructing an integrated simulated container by combining the members of FIG. It is sectional drawing of the simulation container of the form which fastens a fixed mold | type and a movable mold | type with a fixing member. It is an external view of a laminated sheet-like analysis material. It is an external view in the state which inserted the analysis material of FIG. 5 in the cavity part of the simulation container of FIG. (A) And (B) is the external view and sectional drawing of the molded article for analysis shape | molded by compressing material with the movable mold | type from the state of FIG. It is an external view of an example of the resin molded product which has an uneven | corrugated site | part on the surface.

The resin fluidity simulation method of the present invention will be described with reference to the drawings.
As described above, the present invention is a method for analyzing the flow behavior of a resin inside a molding die when a resin molded product is molded by a compression molding method, and conforms to the whole or part of the shape of the resin molded product to be molded. Using the simulated container provided with the hollow portion, the analytical material is filled in the hollow portion of the simulated container, and this is compressed and cured in the simulated container to mold the analytical molded product. And the flow behavior of the resin at the time of actual molding is analyzed by verifying and evaluating the state of the surface shape or the cross section of the analytical molded product.

  Specifically, for example, when a resin molded product 1 having a reverse T-shaped cross section having ribs 1a shown in FIG. 1 is molded by a compression molding method, the whole or a part of the resin molded product 1 is analyzed using a simulated container. Molding the molded product, verifying the filling degree of the resin in the analytical molded product and the fluidity of the resin to the uneven part of the molded part, especially the flow state of the filler to the uneven part in the resin molded product containing the filler. Therefore, the fluidity of the resin in the actual molding die is predicted and reflected in the product design.

FIG. 2 shows one form of the simulated container 2 used for molding the resin molded product 1 shown in FIG.
This simulated container 2 is a molded container made of synthetic resin molded by a 3D printer, and a pair of mold halves 21a and 21b that form a cavity 2a that is a material filling region at the upper part by joining face to face. And the fixed mold 21 consisting of the mold part 21c fitted to the outer periphery of the connected mold halves 21a and 21b, and the material filled in the cavity 2a by covering the upper surface of the fixed mold 21 and pressing downward. It is comprised by the movable type | mold 22 which compresses. The inner surface of the hollow portion 2 a is formed in an uneven shape along the surface shape including the rib 1 a of the resin molded product 1.

As shown in FIG. 3, the fixed mold 21 of the simulated container 2 is obtained by joining the mold halves 21a and 21b face to face (FIG. 3A) and fitting the mold part 21c on the outer periphery thereof. The cavity portion 2a that is assembled (in the same figure (B)) and is provided in the inner surface shape along the whole or a part of the resin molded product is arranged on the upper part of the assembled fixed mold 21.
Then, the cavity portion 2a is filled with the analysis material, the upper portion of the cavity portion 2a is closed with the movable mold 22 (FIG. 3C), and the filled material is pressed downward and compressed with the movable mold 22. Thus, the shape of the inner surface of the cavity 2a is transferred to the analysis material that has flowed through the cavity 2a, and the analysis molded product is formed.
As shown in FIG. 4, the simulated container 2 is filled in the fixed mold 21 with the movable mold 22 by clamping the fixed mold 21 and the movable mold 22 via fixing members 23 and 23 such as bolts and nuts. The analysis material thus formed may be compressed.

  Hereinafter, the Example when the resin fluidity | liquidity in the case of shape | molding the resin molded product 1 (base material thickness 5mm, rib 1a thickness 4mm, rib 1a height 15mm) shown by FIG. 1 is simulated is demonstrated.

<Example 1>
As a material for analysis, a sheet-like SMC material obtained by adding AIBN (azobisisobutyronitrile), which is styrene and a radical initiator, to polyester obtained by condensation reaction of maleic anhydride and glycol was used. . The fiber volume content relative to the entire SMC material used was set to 30%.

As the simulated container 2, the container composed of the fixed mold 21 and the movable mold 22 shown in FIGS. 2 and 3 was used.
The simulated container 2 was produced using a 3D printer using polyetherimide (product name “ULTEM 9085 Model”: glass transition temperature 186 ° C., manufactured by STRATASYS) as the molding material. The glass transition temperature is obtained from the tan δ peak temperature by measuring the dynamic viscoelasticity of the resin material.

A sheet-like SMC material (maximum reaction heat temperature: 200 ° C.) having a thickness of 2 mm obtained by the above method is laminated, and this is placed in the cavity 2 a of the fixed mold 21 of the simulated container 2. The movable mold 22 was put on the upper opening of the plate, and the filled material was pressurized with the movable mold 22. The pressurization was performed by placing the simulated container 2 in a press machine so that the pressurization was the same as in normal press molding.
After the pressure treatment, the simulated container 2 filled with the SMC material was left still in an oven having an atmospheric temperature of 150 ° C., and taken out of the oven after 30 minutes.

  When the movable mold 22 of the simulated container 2 taken out of the oven is removed and the inside is confirmed, the SMC material is sufficiently cured by undergoing a curing reaction, and is further removed from the fixed mold 21 so that the shape shown in FIG. A molded product for analysis was obtained.

<Example 2>
Example 1 except that the simulated container 2 was manufactured using a polycarbonate (product name “PC-ISO Model (Translucent)”: glass transition temperature 161 ° C.) manufactured by STRATASYS, Inc .: glass transition temperature 161 ° C.) as a molding material using a 3D printer. A molded article for analysis was produced under the same conditions, and simulation of resin fluidity was performed.

  As a result, when the movable mold 22 of the simulated container 2 taken out of the oven is removed and the inside is confirmed, the SMC material is sufficiently cured by undergoing a curing reaction, and is further removed from the fixed mold 21 and shown in FIG. A molded product for analysis having the shape thus obtained was obtained.

<Example 3>
Commercially available clay was used as the analysis material.
Two types of clay, red and white, are used, and a plurality of commercially available mechanical pencil cores folded to a length of about 5 mm are mixed in as fillers. As shown in FIG. 11a and white clay 11b were alternately stacked with a thickness of 2 mm to form a four-layered material for analysis 11.

As the simulated container 2, the container composed of the fixed mold 21 and the movable mold 22 provided with the fixing member 23 shown in FIG. 4 was used.
The simulated container 2 uses acrylonitrile-styrene-acrylic acid ester (ASA resin) (product name “ASA Model (Natural)”: glass transition temperature 108 ° C., manufactured by STRATASYS) as a molding material, using a 3D printer. Produced.

As shown in FIG. 6, the analysis material 11 is placed in the cavity 2 a of the fixed mold 21 of the simulation container 2, and the movable mold 22 is put on the upper opening of the fixed mold 21, and the filled material is moved to the movable mold. By pressurizing at 22, the flow of the material was promoted, and the inside of the container was filled.
The pressurization was performed by using bolts and nuts, which are fixing members 23 provided in the container, and fastening the fixed mold 21 and the movable mold 22 with bolts to tighten both molds with the force of the bolts.

After the pressure treatment, when the bolt is removed and the fixed mold 21 and the movable mold 22 are separated, the clay as the analysis material 11 is cured, and the analysis molded article 1 having the shape shown in FIG. was gotten.
When the base portion of the analytical molded article 1 was cut, the flow state of the material could be observed from the cross section due to the difference in color as shown in FIG.
Further, as a result of observation, the core mixed in the material was directed in the direction along the flow of the clay, and the fiber orientation behavior as seen in the SMC material containing glass fiber was confirmed.
From this point of view, it has been found that resin flow and fiber orientation can be simulated by using simulated materials such as colored clay and a core.
In this way, it is possible to know where the colored layers of colored clay flow in the flow process, and it is possible to easily predict the fiber orientation by looking at the direction of the core-like object.

(Comparative example)
A simulated product 2 was produced under the same conditions as in Example 1 except that a simulated container 2 was produced using a 3D printer using ASA resin as a molding material, and a resin fluidity simulation was performed.

  As a result, when the movable mold 22 of the simulated container 2 taken out of the oven is removed and the inside is confirmed, deformation of the simulated container 2 itself due to its own weight at high temperatures is confirmed, and this shape deformation causes the SMC material and the inner surface of the cavity 2a to be deformed. The molded product for analysis having a desired shape could not be obtained.

From the above examples and comparative examples, when molding the SMC material, if the simulated container 2 using the resin material having a high glass transition temperature Tg is produced and the molded article for analysis is molded using this, the appropriate It was confirmed that an analytical molded product capable of evaluating the resin molded product was obtained. In addition, it has been found that appropriate design information can be obtained by evaluating the molded article for analysis.
Further, in a simple simulation such as using clay as an analysis material, the actual flow of resin, fibers, fillers, etc. can also be obtained by using a simulated container 2 made of a material having a low glass transition temperature such as ASA resin. It has been found that useful information about the orientation can be obtained.

  In addition, the shape and form of the illustrated resin molded product 1 and the simulated container 2 are examples, and the present invention is not limited to the illustrated configuration and form. Moreover, the resin material used for the shaping | molding shown in the Example is an example.

DESCRIPTION OF SYMBOLS 1 Resin molded product (analysis molded product), 2 Simulated container, 2a Cavity, 21 Fixed type, 22 Movable type, 23 Fixing member

Claims (8)

It is a method for analyzing the flow behavior of the resin inside the molding die when molding a resin molded product by the compression molding method,
Produce a simulated container with a cavity along the shape of the whole or part of the resin molded product to be molded,
Filling the cavity of the simulated container with the analytical material made of resin or soft material used for the molding, and molding the molded article for analysis by compressing in the simulated container,
A resin fluidity simulation method for analyzing the flow behavior of a resin during actual molding of the resin molded product by verifying and evaluating the strength or cross-sectional state of the molded product for analysis.   The method for simulating resin fluidity according to claim 1, wherein a simulated container made of synthetic resin is used.   The method for simulating resin fluidity according to claim 2, wherein a simulation container made by a 3D printer is used.   The resin fluidity simulation method according to any one of claims 1 to 3, wherein a laminated resin sheet material is used as an analysis material.   The resin fluidity simulation method according to any one of claims 1 to 4, wherein a filler-containing resin is used as an analysis material. The glass transition temperature Tg (° C) of the synthetic resin constituting the simulated container and the maximum temperature Tmax (° C) during compression molding of the resin used as the analysis material satisfy the following formula (1): 6. The resin fluidity simulation method according to any one of items 1 to 5.
Formula (1): −100 (° C.) ≦ Tg−Tmax ≦ 300 (° C.)   7. The resin fluidity simulation method according to claim 6, wherein the glass transition temperature Tg of the synthetic resin constituting the simulated container is 100 [deg.] C. or higher.   8. The resin fluidity simulation method according to claim 1, wherein a simulation container having a structure in which a fixed mold and a movable mold are clamped via a fixing member is used.

Images