JP5525912B2 - Method for identifying deformation cause part of resin molded product and method for suppressing deformation defect - Google Patents

Description

  The present invention relates to a method for identifying a region on the surface of a resin molded product that causes shrinkage that causes a deformation defect that occurs after the resin molded product is removed from the mold, and the resin molded product after being removed from the mold. The present invention relates to a deformation defect suppressing method for suppressing deformation defects.

  Resin-molded products are used in various fields because they have the characteristics of being inexpensive and lightweight without corrosion like metals and wood. Moreover, in order to save earth resources by recycling, most of the resin molded products are formed from thermoplastic resins. Various molding methods such as compression molding, transfer molding, injection molding, extrusion molding, and blow molding are used. Due to advances in molding machines and mold structures, it is possible to easily mold resin molded products with complex shapes. ing.

  In particular, the production of resin molded products by injection molding has advantages such as good productivity and the ability to easily mold complex shapes, so it covers a wide range from industrial products to daily goods. It is done in

  The resin molded product immediately after being taken out from the injection mold is hot. The resin molded product is cooled after being taken out, but the resin molded product is deformed by the temperature change from the high temperature state to the low temperature state. The deformation of the resin molded product does not uniformly deform the entire molded product. For this reason, problems such as warp deformation (hereinafter sometimes referred to as deformation problems) occur in the resin molded product.

  In order to reduce such deformation defects, deformation analysis of a resin molded product is performed. Specifically, analysis is performed using analysis software from a design shape model of a resin molded part based on molding conditions, a molding machine, characteristics (physical properties) of a resin material to be used, and the like (Patent Document 1).

JP 2007-71674 A

  Even if the conventional deformation analysis as described in Patent Document 1 is performed, the position causing the deformation failure cannot be identified, and it takes time and labor to determine suitable molding conditions.

  The present invention has been made to solve the above-mentioned problems, and its purpose is to facilitate the region on the surface of the resin molded product that causes shrinkage that causes deformation failure after the resin molded product is taken out of the mold. Is to provide a method for determining a suitable molding condition based on the shrinkage behavior of the specified region and suppressing deformation defects.

  The inventors of the present invention have made extensive studies in order to solve the above problems. As a result, the step of deriving the distribution of shrinkage rate based on the distribution of the amount of displacement on the surface of the resin molded product after taking out from the mold, and the region having a larger shrinkage rate than the surroundings is deformed based on the distribution of shrinkage rate. If it is a method provided with the process of specifying as an area | region which produces the shrinkage | contraction which causes a defect, it discovered that the said subject was solved and came to complete this invention. More specifically, the present invention provides the following.

  (1) A step of deriving a shrinkage rate distribution based on the displacement distribution on the surface of the resin molded product after taking out from the mold, and a region having a larger shrinkage rate than the surroundings is deformed based on the shrinkage rate distribution. A method of identifying a cause of deformation failure comprising: a step of identifying as a region causing shrinkage that causes failure.

  (2) The method for identifying the cause of deformation failure according to (1), wherein the region having a large shrinkage rate is a region having the largest shrinkage rate.

  (3) A deformation defect suppressing method for suppressing a deformation defect of a resin molded product after being taken out from the mold, the step of deriving a distribution of shrinkage rate on the surface of the resin molded product after being taken out from the mold, and the shrinkage Identifying a region having a larger shrinkage rate than the surroundings as a region causing shrinkage that causes deformation failure, and determining molding conditions for suppressing the shrinkage rate of the region having a larger shrinkage rate based on the distribution of the rate, A deformation defect suppressing method comprising:

  (4) The deformation failure suppression method according to (3), wherein the region having a large shrinkage rate is a region having the largest shrinkage rate.

  ADVANTAGE OF THE INVENTION According to this invention, the area | region on the resin molded product surface which produces the shrinkage | contraction which becomes the cause of the deformation | transformation defect which generate | occur | produces after taking out a resin molded product from a metal mold | die can be specified easily. In this way, since the position where the shrinkage causing the deformation failure is easily determined, the molding conditions that suppress the change in the shrinkage amount of the region causing the deformation failure can be easily determined. It can be easily suppressed.

(A) is a figure which shows the plate-shaped resin molded product provided with the irregular spotted pattern, (b) shows the state which divided | segmented the surface of the resin molded product provided with the irregular spotted pattern into several area | regions. It is a figure, (c) is a figure which shows the one part enlarged view of the some area | region shown in (b). (A) is a figure which shows a mode that a deformation | transformation of a resin molded product is measured by an imaging | photography means, (b) is a figure which shows the resin molded product after a deformation | transformation, (c) is an expansion of the resin molded product before a deformation | transformation. It is a figure which shows a figure, (d) is a figure which shows the enlarged view of the resin molded product after a deformation | transformation. It is a figure which shows the resin molded product used in Example 1. FIG. It is a figure which shows the result of the shrinkage | contraction rate distribution of the resin molded product of Example 1. FIG. It is a figure which shows the deformation | transformation state of the resin molded product of Example 1. FIG.

  Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present invention. . In addition, although description may be abbreviate | omitted suitably about the location where description overlaps, the summary of invention is not limited.

<Method for identifying the cause of deformation defects>
The method for identifying the cause of deformation failure according to the present invention is a step of deriving the distribution of shrinkage based on the distribution of the amount of displacement of the surface of the resin molded product after being taken out from the mold (hereinafter referred to as “first step”). And a step of identifying a region having a larger shrinkage rate than the surroundings as a region causing shrinkage that causes a deformation failure (hereinafter sometimes referred to as a “second step”) based on the distribution of the shrinkage rate. Prepare. Hereinafter, each step will be described.

[First step]
The first step is a step of measuring the distribution of shrinkage rate based on the amount of displacement in each region after the surface of the resin molded product is divided into a plurality of regions and the resin molded product is taken out of the mold.

  The resin material for molding the resin molded product is not particularly limited, and a conventionally known resin material can be used. A resin mixture obtained by blending a plurality of resin materials is also included in the resin material. In addition, additives such as nucleating agent, carbon black, pigments such as inorganic fired pigments, antioxidants, stabilizers, plasticizers, lubricants, mold release agents, and flame retardants are added to the resin to achieve desired characteristics. The provided resin material is also included.

  The shape of the resin molded product is not particularly limited, and the present invention can be applied to any shape of the resin molded product. Deformation defects such as warp deformation for the purpose of improvement in the present invention tend to be a problem in the case of unevenly formed products. This is because an uneven molded product includes a thick portion and a thin portion in one molded product, and the thick portion and the thin portion tend to have different deformation behaviors. The present invention is most suitable for improving the deformation failure of such uneven thickness molded products.

Hereinafter, an example of derivation of the shrinkage rate distribution will be described. For example, the shrinkage distribution can be measured by the following method.
The surface of a resin molded product with an irregular pattern is divided into multiple regions, and the amount of deformation between each region is measured from one region as a pattern, and the shrinkage rate is based on this displacement. A distribution can be derived.

  Examples of the “irregular pattern” include an irregular spotted pattern, a streaky pattern, a marble pattern, and a leather pattern. The pattern may be a planar pattern or a three-dimensional pattern. Moreover, the method to attach a pattern is not specifically limited, The method etc. which attach a pattern with a spray are mentioned.

  “Division into a plurality of regions” will be described with reference to the drawings. FIG. 1A shows a plate-shaped resin molded product 1, which has a spotted pattern 11. FIG. 1B shows a state in which the surface of the plate-shaped resin molded product 1 is divided into a plurality of regions 12.

  As shown in FIG. 1 (c), “one area is one pattern” means that each divided area 12 is substantially divided when the spot pattern 11 in each area 12 is made into one pattern as a whole. It means that they are all recognized as different symbols. That is, as shown in FIG. 1C, it means that the design of the area A is different from the designs of the areas B, C, and D.

  Next, measurement of the displacement amount will be described. The distribution of the displacement amount can be derived by obtaining the displacement amount in a plurality of areas as follows. Then, the contraction rate distribution can be derived from the derived displacement amount distribution. The measurement of the amount of displacement can be derived from the amount of displacement between symbols in the region, the amount of displacement of symbols, and the like. Although the measuring method of a displacement amount is not specifically limited, It is preferable to measure without making a measuring instrument etc. contact a resin molded product. This is because when the measuring instrument is brought into contact with the resin molded product, the amount of deformation may not be measured accurately due to the influence of an adhesive for contact.

  A method for measuring the displacement amount without contact is not particularly limited, but an example of a method for measuring the displacement amount without contact is shown in FIGS.

  FIG. 2A shows a state in which the resin molded product 2 having an irregular spot pattern is photographed by the photographing means 3. The resin molded product 2 shown in FIG. 2 (a) is in a state of being hardly contracted immediately after being taken out from the mold. The photographing means 3 is for measuring the amount of displacement, but a method of measuring the amount of displacement using the photographing means such as a CCD camera as described above is preferable. This is because it is easy to accurately measure the amount of displacement if it is a method using a photographing means such as a CCD camera. Furthermore, a large amount of displacement can be easily measured by expanding the photographing region of the camera. By enlarging the imaging range at a predetermined magnification, a small amount of displacement can be easily measured. That is, even when the amount of displacement is small, the entire displacement amount distribution can be derived easily and accurately by expanding the photographing range and measuring the amount of displacement in several steps. As a result, a shrinkage ratio distribution can be obtained easily and accurately.

  FIG. 2B shows the resin molded product 2 after being contracted by cooling after being taken out from the mold. As a whole, ΔX contracts in the X direction and ΔY contracts in the Y direction. When the resin molded product 2 contracts almost uniformly as a whole, the amount of displacement in such a large region may be obtained, but in reality, the amount of displacement and the deformation direction vary within the resin molded product. Very often.

  FIG. 2C is a view similar to FIG. 1C and shows an enlarged view of the resin molded product before deformation. That is, FIG. 2 (c) shows a state in which the sheet is hardly contracted immediately after being taken out from the mold. FIG. 2 (d) shows an enlarged view of the resin molded product at the same position as FIG. 2 (c) after shrinkage by cooling after taking out from the mold.

As shown in FIG. 2 (c), the distance between adjacent regions before shrinkage (between the region B and the region C) is assumed to be X _A. As shown in FIG. 2D, it is assumed that the distance between the regions becomes X _A ′ after contraction. At this time, the displacement amount is (X _A −X _A ′), and the contraction rate is {(X _A −X _A ′) / X _A } × 100 (%). The contraction rate distribution can be derived by measuring the contraction rate between the regions in the same manner.

  In addition, when deriving the shrinkage rate distribution, the method is not limited to the method using the distance between the regions as described above. Further, the division into the fine regions as described above is for measuring the local displacement amount, and any method is preferable as long as it is a method for measuring the local displacement amount of the resin molded product surface. Can be adopted.

  In addition, this invention is applicable also to the resin molded product which does not have a pattern. In the case of a resin molded product having no pattern, it is necessary to add a pattern after molding. Since the shrinkage starts immediately after taking out from the mold, it is preferable to apply the pattern to the resin molded product immediately after taking out from the mold.

  The analysis can be performed if the area is set so that the pattern can be recognized. For this reason, even if the spots are large, there is no problem if the area is set large accordingly. Therefore, the optimum pattern size varies depending on the size of the region. That is, the area is set according to the size of the spots. Further, by dividing the surface of the resin molded product into a plurality of regions so that the distance between the regions is short, more accurate measurement can be performed. When taking measurements using a CCD camera or other photographic means, the distance between the areas can be shortened by enlarging the photographic area or changing to a camera with higher pixels, enabling high-precision measurements. become.

  Measurement of the amount of deformation with a speckled pattern using a CCD camera as described above can be performed using, for example, a digital 3D-correlation system VIC-3D (manufactured by Correlated Solutions).

[Second step]
In the second step, based on the shrinkage rate distribution derived in the first step, a region having a higher shrinkage rate than the surroundings is specified as a region causing shrinkage that causes deformation failure. If there is a part where the shrinkage rate is locally large, this part causes a deformation failure. Although a portion having a large shrinkage rate is not necessarily greatly deformed, according to the first step of the present invention, a portion having a large shrinkage rate that causes a deformation failure can be easily identified.

  In addition, the region where the shrinkage rate is the largest is likely to cause a large deformation failure, but according to the present invention, the position where the shrinkage rate is the largest can be easily identified.

<Deformation defect suppression method>
The deformation defect suppressing method of the present invention derives a molding condition for suppressing the shrinkage of the portion where the shrinkage rate is locally confirmed from the shrinkage rate distribution. The molding conditions are determined based on the position of the portion where the shrinkage rate locally increases and the amount of displacement. Here, the molding conditions include not only general molding conditions such as setting conditions of the molding apparatus but also the conditions of the shape of the resin molded product.

  For example, in the case of a resin molded product formed by molding an unfilled resin material, the shape of the resin molded product (thick part, position of thin part, ratio of thin part), temperature distribution in the mold, pressure distribution Greatly affects deformation such as warpage of the resin molded product. Therefore, particularly in the case of an unfilled resin material, the deformation of the resin molded product can be suppressed by examining the shape of the resin molded product. The unfilled resin material amount refers to a resin material that does not contain a reinforcing inorganic filler such as glass fiber.

  When considering the shape of the resin molded product in order to eliminate deformation such as warpage that occurs in the resin molded product formed by molding the amount of the unfilled resin material, a change to make the portion where the shrinkage rate is large thinner. Deformation defects tend to be eliminated by changing the molding conditions, such as changing the surrounding area of the portion with a large shrinkage ratio to be thick, or changing the mold to enhance the cooling of the mold only at the portion with a large shrinkage rate.

  In addition, the deformation failure may not be resolved by changing the molding conditions once. This is because the solution of the cause of one deformation defect is often not reflected in the whole. For this reason, by changing the molding conditions several times, considering the suitable molding conditions from the location where the shrinkage rate locally increases in each molded product, the amount of displacement, molding conditions that do not easily cause deformation defects Can be determined.

  Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

<Resin material>
Unfilled polyacetal resin: Duracon M90-44 (manufactured by Polyplastics)

<Example 1>
A resin molded product having a shape and dimensions as shown in FIG. 3 was produced by an injection molding method. Within 5 seconds after the resin molded product was removed from the mold, pigment ink was sprayed onto the resin molded product to give an irregular spot pattern on the surface of the resin molded product.

  Using a digital 3D-correlation system VIC-3D (manufactured by Correlated Solutions), the surface of the resin molded product is divided into a plurality of regions, and using these regions, the amount of local displacement is measured, and the shrinkage distribution is obtained. Derived. The measurement time is 5 minutes after the resin molded product is taken out of the mold. In addition, since the surface of the resin molded product can be instantaneously divided into a plurality of regions, and the measurement of the deformation amount can be started at the same time as the division into a plurality of regions, the substantial measurement time is 5 minutes after applying the pattern. is there.

  The shrinkage ratio distribution obtained as described above is shown in FIG. Furthermore, the figure which shows an actual deformation | transformation state was shown to Fig.5 (a). As is clear from the results shown in FIG. 4A, the rib portion has an average shrinkage of 1.5%, and the base portion has an average shrinkage of 0.77%. It was confirmed that there was a large difference between the shrinkage rate of the base portion. From this result, it was inferred that the thickness of the rib portion was thick as the cause of the deformation failure.

[Change of molding conditions 1]
Since it was presumed that deformation defects were caused due to the thickness of the rib portion, the shape was changed to the following.
Shrinkage distribution was obtained in the same manner as the resin molded product except that the rib thickness was changed to 2 mm and the base thickness was changed to 4 mm. The resulting shrinkage distribution is shown in FIG. Moreover, the figure which shows an actual deformation | transformation state was shown in FIG.5 (b). As is apparent from the results shown in FIG. 4B, the rib portion has an average shrinkage of 0.48%, the base portion has an average shrinkage of 1.03%, and the rib portion has a shrinkage rate. It was confirmed that there is a large difference between the shrinkage rate of the base portion and the base portion. From this result, it was estimated that the thickness of the base portion was thick as a cause of the deformation failure.

[Change of molding conditions 2]
Since it was estimated that a deformation defect would occur when the base portion was uniformly thick, the shape was changed to the following. Shrinkage distribution was obtained in the same manner as the resin molded product, except that the rib thickness was changed to 2 mm and the base thickness was changed to a continuously changing thickness. Continuously changing means that the thickness changes in the Y direction from 2 mmt to 6 mmt (Y = 0 is 2 mmt). The obtained shrinkage ratio distribution is shown in FIG. Moreover, the figure which shows an actual deformation | transformation state was shown in FIG.5 (c). As is clear from the results shown in FIG. 4C, the shrinkage rate is 0.52% on average when the thickness of the base portion is 2 mmt, and 1.32% on the average when the thickness is 6 mmt. It was confirmed that there was a large difference between the shrinkage rate of the thin portion of the base portion and the shrinkage rate of the thick portion of the base portion. From this result, it was speculated that the thickness of the base portion continuously changed was the cause of the deformation failure.

[Change of molding conditions 3]
Judging from the above results, the rib thickness was changed to 2 mmt, and the base thickness was changed to 2 mmt. After the production of the resin molded product, the shrinkage distribution was obtained in the same manner as described above. The resulting shrinkage distribution is shown in FIG. Moreover, the figure which shows an actual deformation | transformation state was shown in FIG.5 (d). As apparent from the results shown in FIG. 4D, the rib portion has an average shrinkage of 0.62%, and the base portion has an average shrinkage of 0.56%. It was confirmed that there was almost no difference between the shrinkage rate of the base part and the base part. As shown in FIG. 5D, the resin molded product hardly deformed.

DESCRIPTION OF SYMBOLS 1, 2 Resin molded product 11 Spot pattern 12 Area | region 3 Imaging | photography means

Claims (4)

An irregular pattern is attached to the surface of the resin molded product after being taken out from the mold, the surface of the resin molded product having the irregular pattern is divided into a plurality of areas, and each area is represented as a pattern. Measuring the amount of displacement between each region from the deformation of, and deriving the distribution of shrinkage based on the distribution of the amount of displacement,
A method for identifying a cause of deformation failure, comprising: specifying a region having a shrinkage rate larger than that of the surrounding region as a region causing shrinkage that causes deformation failure based on the distribution of the shrinkage rate.   The method for identifying a cause of deformation failure according to claim 1, wherein the region having a large shrinkage rate is a region having the largest shrinkage rate. A deformation defect suppressing method for suppressing deformation defects of a resin molded product after being taken out from a mold,
An irregular pattern is attached to the surface of the resin molded product after being taken out from the mold, the surface of the resin molded product having the irregular pattern is divided into a plurality of areas, and each area is represented as a pattern. Measuring the amount of displacement between each region from the deformation of, and deriving the distribution of shrinkage based on the distribution of the amount of displacement ,
Identifying a region having a larger shrinkage rate than the surroundings as a region causing shrinkage that causes deformation failure based on the distribution of shrinkage rate, and
Determining a molding condition for suppressing the shrinkage rate of the region having a large shrinkage rate.   The deformation failure suppression method according to claim 3, wherein the region having a large shrinkage rate is a region having the largest shrinkage rate.

Images