JP6283550B2 - Analysis method of fluidization and solidification behavior of resin - Google Patents

Description

  The present invention relates to a method for analyzing the flow solidification behavior of a resin in a mold in injection molding.

  Conventionally, the behavior of fluidization and solidification of resin in a mold in injection molding has been investigated in order to improve the quality of an injection molded product, reduce the size, and reduce costs. Analyzing and grasping the fluidized solidification behavior of the resin at the time of molding is useful for molding in a manner in which warpage deformation is unlikely to occur or for predicting and using warpage deformation. The resin in the mold is cooled by heat release during the holding pressure and cooling process during flow or stopped, and solidifies as the resin temperature decreases. Therefore, in order to grasp the fluidization and solidification behavior of the resin, it is necessary to acquire information on the temperature distribution inside the resin every moment, that is, information on the change over time of the temperature distribution inside the resin. By the way, in order to specify the temperature distribution inside the resin, a method using a correspondence relationship between the dielectric constant of the resin and the temperature of the resin is known. For example, the capacitance between multiple electrodes surrounding the resin is measured, and the dielectric constant distribution inside the resin is reconstructed from the measured values using the dielectric tomography method based on the inverse problem solving method. A method for obtaining a corresponding temperature distribution has been proposed (see, for example, Patent Document 1).

  In addition, in order to analyze the flow solidification behavior of the resin from the flow velocity distribution, the resin flow is measured by a particle image flow velocity measurement method (PIV) in which a tracer such as metal powder is mixed in the resin and the tracer is photographed and tracked with a high-speed camera. A technique for measuring speed is known (for example, see Non-Patent Document 1).

JP 2012-52941 A

Masahiro Seto, Katsu Tanaka, Kazuto Sato, Masaru Yamabe, “Examination of prediction method of physical property value distribution in injection-molded products (2)-Relationship between resin flow velocity distribution in thickness direction and molecular orientation during injection molding -", Molding, Vol. 14, no. 10, pp671-677 (2002)

  However, in the permittivity tomography method as shown in Patent Document 1 described above, it is necessary to obtain measurement data by switching a combination of a plurality of electrodes, and there is a limit to dealing with resin that is injected and moves at high speed. is there. Further, the particle image flow velocity measuring method (PIV) as shown in Non-Patent Document 1 described above cannot be applied unless it is a transparent resin, and the presence of a tracer affects the resin molding in the case of thin-wall molding. There is. In other words, it is possible to perform solidification behavior analysis such as temperature distribution analysis adapted to real time change of solidification phenomenon based on measured values, even for opaque resin and mold, thin wall molding and high speed phenomenon, Further, it is desired that the analysis result can be applied to warpage analysis of a molded product.

  The present invention solves the above problems, can analyze the temperature distribution based on real-time measurement related to the solidification phenomenon, can be applied to high-speed phenomena during injection molding, and is also applicable to opaque resin and thin-wall molding. An object of the present invention is to provide a method for analyzing the flow solidification behavior of a resin that can be applied.

  In order to achieve the above object, the method for analyzing the fluidization behavior of the resin of the present invention is the same as the method for analyzing the fluidization behavior of the resin in the mold in injection molding. The first step of measuring the time-dependent change in the capacitance between the counter electrodes, and the temperature distribution in the die due to the flow solidification behavior of the resin Using the second step of numerically calculating the time-dependent change in temperature and data on the temperature dependence of the dielectric constant of the resin, the temperature distribution in the mold at each time obtained in the second step is converted into a dielectric constant distribution. 3 steps, a fourth step for obtaining a change with time in the capacitance between the opposing electrodes by numerical calculation using the dielectric constant distribution converted in the third step, a capacitance in the first step and a static in the fourth step Find the time scale of the second step where the capacitance is equal, and the time Characterized in that it comprises a fifth step of the temperature distribution of the second step in the scale and time course of the temperature distribution in the mold in the real time scale, the.

  In the analysis method of the fluidized solidification behavior of the resin, the second step may change the time scale by changing the heat transfer coefficient of the wall surface of the mold.

  In the analysis method of the flow solidification behavior of the resin, in the first step, the capacitance is measured by impedance measurement performed by applying an alternating voltage between the counter electrodes, and the measured change in capacitance over time is measured. On the other hand, when the measurement time resolution is insufficient, measurement is performed using an alternating voltage having a higher frequency, and in the third step, data on the temperature dependence of the dielectric constant according to the frequency used in the measurement in the first step is used. You may do it.

  In the analysis method of the flow solidification behavior of the resin, in the first step, the capacitance is measured by impedance measurement performed by applying an AC voltage between the counter electrodes, and the signal level of the measured capacitance is insufficient. In addition, the measurement may be performed using an alternating voltage having a lower frequency, and in the third step, data on the temperature dependence of the dielectric constant according to the frequency used in the measurement in the first step may be used.

  In the analysis method of the flow solidification behavior of the resin, this is an integrated value of shear stress acting on the resin molded in the mold under a time scale that gives a temporal change in the temperature distribution determined in the fifth step. A sixth step for obtaining a distribution of shear strain energy by numerical calculation; a seventh step for obtaining a distribution of molecular orientation of a resin in the molded product by measurement with respect to a molded product molded using a mold; and a reference metal Calculated shear strain energy data obtained from a reference sample molded using a mold and resin, measured molecular orientation data, and linear expansion coefficient having anisotropy associated with these data or Using the measured elastic modulus data, the linear expansion coefficient or elastic modulus data is related to the shear strain energy distribution obtained in the sixth step and the molecular orientation distribution obtained in the seventh step. By performing the 8th step of determining data on the linear expansion coefficient or elastic modulus having anisotropy for the molded product, and using the mold of the first step including a fibrous filler in the resin Ninth step of acquiring data on the three-dimensional orientation of the filler in the molded article to be analyzed, data on the linear expansion coefficient or elastic modulus determined in the eighth step, and data on the three-dimensional orientation of the filler obtained in the ninth step And a tenth step of obtaining data of linear expansion coefficient or elastic modulus having anisotropy in consideration of the filler with respect to the analysis target molded article by numerical calculation.

  In this method of analyzing the fluidization behavior of the resin, the object to be analyzed is molded by an arbitrary mold by performing the sixth to the tenth processes using an arbitrary mold instead of the mold of the first process. You may make it obtain | require the data of the linear expansion coefficient or elastic modulus which has the anisotropy which considered the filler about the goods.

  According to the analysis method of the flow solidification behavior of the resin of the present invention, the real time scale is obtained from the time scale in the numerical calculation based on the real time measurement value of the capacitance between the pair of counter electrodes. Since the change over time of the temperature distribution is obtained, electrode switching is not necessary and it can be applied to high-speed phenomena.

The flowchart about the analysis method of the fluidization solidification behavior of the molten resin which concerns on one Embodiment of this invention. The schematic diagram explaining the analysis method paying attention mainly to the flow of data. Sectional drawing explaining the measurement of the flow and solidification of resin in a metal mold | die, and the electrostatic capacitance of resin. (A) is a figure explaining the time change of the dielectric constant of the resin in the metal mold | die calculated | required from the electrostatic capacitance between electrodes, (b) shows the temperature dependence and measurement frequency dependence of the dielectric constant of resin. Illustration to explain. (A) is a flowchart explaining the modification of the same analysis method, (b) is a flowchart explaining the other modification of the same analysis method. The flowchart about the analysis method of the fluidization solidification behavior of the molten resin which concerns on other embodiment. The schematic diagram explaining the analysis method paying attention mainly to the flow of data. (A) is a top view which shows typically the measurement position of molecular orientation, (b) is a top view which shows the orientation direction and orientation degree in the measurement position of (a) by the inclination and length of an arrow. The top view which shows typically the anisotropic distribution of a linear expansion coefficient. (A) is a diagram qualitatively showing the correlation between the linear expansion coefficient and the molecular orientation in the injection molded product, and (b) is a diagram qualitatively showing the correlation between the linear expansion coefficient and the shear strain energy in the injection molded product. The figure which shows the measurement result of the time-dependent change of the electrostatic capacitance of the resin between the electrodes inject | poured in a metal mold | die and it cools about five different measurement frequencies. The figure which shows the measurement frequency dependence of the measured value of the relative dielectric constant of resin. The figure which shows the measurement result of 5 times performed about the time-dependent change of the electrostatic capacitance of resin cooled in a metal mold | die under fixed molding conditions. The figure which shows the measurement result of 5 times at the time of changing from the shaping | molding conditions of FIG. 13 to another shaping | molding condition. The figure which shows the measurement result of 5 times at the time of changing from the shaping | molding conditions of FIG. 13 to another shaping | molding condition. The figure which shows the measurement result of 5 times at the time of changing from the shaping | molding conditions of FIG. 13 to another shaping | molding condition.

  Hereinafter, a method for analyzing flow solidification behavior of a resin according to an embodiment of the present invention (hereinafter also simply referred to as an analysis method) will be described with reference to the drawings. 1 to 4 show a method for analyzing the flow solidification behavior of a resin that flows and solidifies in a molten state in a mold for injection molding. As shown in FIG. 1 and FIG. 2, the present analysis method uses the temperature distribution T () at each time after the injection of the resin from the basic step (S0) for acquiring the temperature dependence data ε (T) of the dielectric constant of the resin. Steps up to the fifth step (S5) for determining i, t), i = x are provided. The execution order of each of these six steps (S0 to S5) is not limited to the order shown in FIG. 1, but can be executed if the data that can be executed is prepared as shown in FIG. Yes. Therefore, the mutual execution order of each process can be changed suitably. FIG. 2 shows a processing flow focusing on data related to this analysis method. The subscript c attached to the code for displaying each data indicates that the data is a calculated value, and the subscript m indicates that the data is a measured value. Among the symbols representing each data, for example, the symbols representing the distribution such as the temperature distribution T (i, t) are omitted from the display of the spatial coordinates. Hereinafter, each process is demonstrated in order.

  The basic step (S0) is a step of acquiring data ε (T) on the temperature dependence of the dielectric constant or relative dielectric constant of a resin having the same composition as the resin used for injection molding. Such data ε (T) is obtained by measuring the capacitance of the resin disposed between the counter electrodes under a constant temperature condition where the temperature T is constant, and by sequentially changing the temperature T. It is obtained by converting the measured value of the capacitance into a dielectric constant or a relative dielectric constant. Further, the temperature dependence data ε (T) of the dielectric constant of the resin may be obtained by calculation based on data such as the molecular structure of the resin, and is a function of a semi-empirical formula that combines the calculated value and the actually measured value. It may be obtained as an expression.

(First step)
As shown in FIG. 3, the first step (S1) uses a pair of counter electrodes 3 provided on the wall surface 10 of the mold 1 so as to sandwich the resin 2 flowing in the mold 1, and the counter electrodes This is a step of obtaining the capacitance Cm (t) at each time t of the resin 2 that flows and solidifies between three. The mold 1 is made of, for example, an insulator (dielectric) such as ceramic so as not to affect the measurement of capacitance. The counter electrode 3 is connected to an impedance analyzer 30 that measures the impedance between the electrodes by applying a voltage of a predetermined frequency between the electrodes. The capacitance is measured by impedance measurement.

  The capacitance Cm (t) is a function of the position in the mold 1 in the sense that it is a measured value at the position where the counter electrode 3 is disposed in the mold 1. If necessary, the distribution of the capacitance Cm (t) in the mold 1 can be obtained by arranging and measuring a pair of counter electrodes 3 at various locations on the opposite wall surfaces of the cavity in the mold 1. The capacitance Cm (t), which is a measurement value in real time, shows a change with time that changes with the passage of time t. The change with time of the capacitance Cm (t) is caused by the temperature change of the resin 2 to be measured, and the change with time reflects the flow solidification behavior of the resin 2.

  The mold 1 constitutes a cavity that is a space filled with the injected resin 2. The resin 2 flows along the flow direction MD and grows the solidified resin layer 2a from the wall surface 10 side of the cavity. The solidified resin or the non-solidified resin 2b that has reached a dead end stops flowing. In the figure, the flow velocity distribution between the wall surfaces 10 is schematically shown. The closer the non-solidified resin 2b is to the mold 1 and the solidified resin layer 2a, the more it is cooled and the viscosity is increased. Accumulate shear stress as energy of internal strain and stop.

(Second step)
In the second step (S2), the mold 1 is modeled, and the counter electrode is formed in the mold 1 under a plurality (n) of different calculation conditions J (i), i = 1,. In this step, the temperature distribution T (i, t) of the resin 2 at each time t when it flows and solidifies between three is calculated by numerical calculation. The data of the temperature distribution T (i, t) is acquired by calculation using three-dimensional resin flow analysis software. A plurality of different calculation conditions J (i) are conditions for changing the temporal change of the temperature distribution T (i, t) of the resin 2. Therefore, for example, the heat transfer coefficient of the wall surface 10 of the mold 1, that is, the level of heat transfer between the wall surface 10 and the resin 2 is set as the calculation condition.

  Between conditions with different heat transfer rates, the heat flow rate flowing from the resin 2 to the mold 1 is different, the cooling process of the resin 2 is different, and the temperature distribution T (i, t) changes with time. That is, the time scale of the temporal change of the temperature distribution T (i, t) differs between conditions having different heat transfer coefficients. Therefore, by changing the heat transfer coefficient and making the calculation conditions different from each other, it is possible to adjust the temporal change of the temperature distribution T (i, t) of the resin 2, that is, the time scale. In general, when the cooling process is changed, not only the time scale of the same temperature distribution changes, but also the temperature spatial distribution changes, the time dependence also changes, and the temperature distribution changes over time. It changes spatially. Therefore, for example, paying attention to the time until the temperature of the resin to be fluidized and solidified becomes a predetermined temperature or less, such a time may be changed by changing the heat transfer coefficient. The heat transfer coefficient affects the temperature change and solidification behavior of the resin 2, affects the flow rate of the resin 2, and further generates a shear exotherm term (a change in strain rate associated with solidified layer growth and This affects the effect of the term representing the heat generation due to the change in shear viscosity accompanying resin cooling.

(Third step)
In the third step (S3), the temperature distribution T (i, t) of the resin 2 obtained in the above second step using the temperature dependence data ε (T) of the dielectric constant obtained in the above basic step. ) Is converted into the dielectric constant distribution ε (i, t) of the resin 2 respectively.

(4th process)
In the fourth step (S4), the capacitance Cc (i, i) generated by the resin 2 between the counter electrodes 3 under the respective dielectric constant distributions ε (i, t) converted in the third step described above. t) is a step of calculating each.

(5th process)
In the fifth step (S5), a time scale of the second step in which the capacitance Cm (t) of the first step and the capacitance Cc (i, t) of the fourth step are equal is obtained, and the time scale In this step, the temperature distribution T (i, t) is changed with time in the temperature distribution in the mold on a real time scale. This process is a process for matching changes with time, and is a process for matching the time scales in the time dependence of the actually measured values and the calculated values. In other words, it is a process of selecting a change over time that matches the change over time of the measured value of the capacitance Cm (t) from among the change over time of the calculated value of the capacitance Cc (i, t). The selection is performed using, for example, a cross-correlation function between data based on the degree of pattern matching between temporally changing waveforms. By this selection, the parameter i of the calculation condition J (i) is determined, the temperature distribution T (i, t) of the resin 2 between the counter electrodes 3 is determined, and the change with time is determined. The capacitance Cc (i, t) is a calculated value calculated through the third step and the fourth step based on each of a plurality of different calculation conditions J (i) in the second step. Further, the capacitance Cm (t) is a measured value obtained in the first step. Thus, by obtaining the temperature distribution T (i, t) of the resin 2 and its change with time, the fluidization and solidification behavior of the resin 2 that flows and solidifies in the molten state in the mold 1 can be grasped.

  In this analysis method, a suitable temperature distribution is determined from the temperature distribution T (i, t), which is a result based on a local calculation, based on the capacitance Cm (t) that is a global measurement value. The temperature dependence of the data ε (T) of the dielectric constant of the resin is used for the determination. This is based on the fact that the dielectric constant of the resin is a physical property value and can be applied to a local phenomenon.

  As described above, a calculation result that matches the time-dependent change indicated by the measurement value from the time-dependent change indicated by the plurality of types of time functions under a plurality of different calculation conditions J (i). Selecting means that one calculation condition J (i), i = x is determined. This means that the heat transfer coefficient used as the calculation condition J (i) is determined, and the temperature distribution T (i, t), i = x is determined.

  Further, the heat transfer coefficient used as the calculation condition J (i) is not a physical property value but depends on the surface state of the mold 1 and the temperature and flow velocity of the resin 2 in contact with the surface of the mold 1. The dependency may be appropriately approximated or reflected in the numerical calculation with higher accuracy.

  According to the present embodiment, the real time scale is obtained from the time scale in the numerical calculation based on the capacitance Cm (t) that is the real time measurement value between the pair of counter electrodes 3, and the temperature distribution changing with time. Since T (i, t) is obtained, it is not necessary to switch electrodes and can be applied to a high-speed phenomenon. The processing for obtaining the real time scale is performed by calculating the capacitance Cm between the pair of counter electrodes 3 from the result of the plurality of temperature distributions T (i, t) of the resin 2 calculated under the plurality of calculation conditions J (i). This is performed by selection based on the actually measured value of (t). Further, in the present embodiment, since the actual measurement value used for the analysis is a measurement result of the capacitance between the pair of counter electrodes, unlike the case of using the conventional PIV method, even if it is an opaque resin or mold, Applicable to thin wall molding and high speed phenomenon. Further, by disposing the counter electrode at an appropriate position of the mold, measuring the capacitance Cm (t) at each position, and determining the temperature distribution T (x, t) at each position, the temperature of the resin The change with time of the distribution can be grasped in more detail.

(Modification)
4 and 5 show a modification of the above-described embodiment. As shown in FIGS. 4A and 4B, after the resin 2 is injected, it is rapidly cooled in the mold 1 in a short time, and the relative dielectric constant εr of the resin 2 decreases with the cooling. . In addition, the relative dielectric constant εr differs in the measured value obtained when the frequency used for the measurement is different. In general, the lower the measurement frequency, the larger the measured value of the relative dielectric constant εr, and the higher the sensitivity of the capacitance measurement, and the higher the measurement frequency, the smaller the measured value of the relative dielectric constant εr. The sensitivity of is low. In addition, the lower the measurement frequency, the longer the cycle and the lower the time resolution for capacitance measurement, and the higher the measurement frequency, the shorter the cycle and the time resolution for capacitance measurement.

  Therefore, as shown in FIG. 5A, when measuring the capacitance by impedance measurement in the first step (S1) described above, a predetermined measurement frequency is set (S11), and the time resolution is insufficient. In this case (NO in S12), the frequency is reset to a higher frequency (S13). If the time resolution is sufficient (YES in S12), the measurement is executed (S14). That is, when measuring the capacitance Cm (t), if the measurement time resolution is insufficient with respect to the speed of change in the measured capacitance with time, the measurement is performed using an AC voltage having a higher frequency. In actual measurement, it is difficult to change the frequency during measurement, so it is necessary to investigate in advance the speed of time change of the measurement target in injection molding and decide which measurement frequency to use for measurement. Good.

  Further, as shown in FIG. 5B, in the first step (S1) described above, a predetermined measurement frequency is set for measurement (S21), and when the signal level (signal strength) is insufficient (S22). NO), the frequency is reset to a lower frequency (S23). If the signal level is sufficient (YES in S22), measurement is performed (S24). That is, when measuring the capacitance Cm (t), when the signal level of the measured capacitance is insufficient, the measurement is performed using an AC voltage having a lower frequency. In actual measurement, it is only necessary to determine at which measurement frequency the measurement is performed based on a prior investigation, as described above. Note that the level of time resolution and the level of signal level (strength of strength) are in a trade-off relationship with each other, and the measurement frequency may be determined in consideration of both measurement conditions.

(Other embodiments)
6 to 10 show another embodiment of a method for analyzing the flow solidification behavior of a resin. In this embodiment, after the steps shown in FIGS. 1 and 2, the steps shown in FIGS. 6 and 7 are added to analyze the anisotropic distribution of the thermal and mechanical characteristics of the molded product. is there. In the present embodiment, data of thermal and mechanical characteristics having anisotropy is taken into a molded product, and an anisotropy distribution in the molded product is analyzed. Here, the physical property value having anisotropy is, for example, a linear expansion coefficient or an elastic modulus in a molded product molded from a resin containing a fibrous filler. In addition, the orientation of each part of the molded product is fixed by the molecules of the resin itself being fixed inside the molded product in a state where it is aligned in one direction due to shear stress during resin flow solidification. Anisotropy occurs with the distribution of.

  As shown in FIGS. 6 and 7, the analysis method of this embodiment includes five steps from the sixth step (# 1) to the tenth step (# 5) in addition to the steps shown in FIGS. 1 and 2 described above. The process is further provided. The execution order of each of these five steps (# 1 to # 5) is not limited to the order shown in FIG. 6, and as shown in FIG. It has become. Therefore, the mutual execution order of each process can be changed suitably. FIG. 7 shows a processing flow focusing on data related to the analysis method.

(Sixth step)
The sixth step (# 1) is molded under the calculation condition J (x) that gives the temperature distribution T (x, t) determined in the fifth step (S5) and the change with time. In this step, the distribution of the shear strain energy Ec, which is the integrated value of the shear stress acting on the resin 2, is obtained by numerical calculation. The shear strain energy Ec is a value obtained by temporally integrating the shear stress accumulated in the resin while the resin solidifies during the flow in the mold and stops flowing, and the above temperature distribution T (i, t In the same manner as in (), it is obtained by calculation using three-dimensional resin flow analysis software. The shear stress of the resin at the time of injection molding changes every moment in each space in the mold while the resin solidifies while flowing in the mold. Each molecule of the molten resin receives a shearing force during the flow, and the orientation state at the final stop position is determined according to the time for which the force is received. Accordingly, the data of the shear strain energy Ec obtained by integrating the shear stress with time is data including information on the molecular orientation state, more generally anisotropy of the resin molded product. The data of the shear strain energy Ec may be acquired as a vector amount or a tensor amount in association with the flow direction of the resin or the orientation direction of the resin, in addition to acquiring as a scalar value at each part.

(Seventh step)
The seventh step (# 2) is a step for obtaining the distribution of the molecular orientation Gm of the resin 2 in the molded product by measuring the molded product molded using the mold 1. Here, the data on the molecular orientation Gm is data obtained by combining the orientation degree and the orientation direction of the molecules of the resin 2 (for example, liquid crystal polymer molecules). The degree of orientation is an index representing the degree of alignment of the longitudinal direction (angle) of a large number of molecules in a certain region, and the orientation direction is the direction in which the directions of those molecules are most aligned. Data indicating the distribution of molecular orientation Gm is obtained by measurement. For example, as shown in FIG. 8A, the measurement can be performed using a test piece TP cut out from a molded product, and when measurement accuracy is allowed, the molded product is used as it is. You can also.

  In order to acquire data of the local molecular orientation Gm, for example, a measurement method by transmission wide-angle X-ray diffraction having a measurement diameter of 300 μm is used. The degree of orientation is calculated from the half width of the orientation peak appearing in the Debye ring obtained by transmission wide-angle X-ray diffraction. By measurement by such X-ray diffraction, data of distribution of molecular orientation Gm can be obtained with a resolution about the measurement diameter. Three-dimensional data of the molecular orientation Gm can be acquired for each internal point of the injection-molded product from the measurement data at a large number of local measurement points in a large number of test pieces TP cut out in multiple layers from the molded product.

  The data of the molecular orientation Gm is acquired at each measurement point as shown in FIG. 8B, for example. In this figure, the orientation direction is indicated by the vector direction, and the degree of orientation is indicated by the vector length. In FIG. 8B, the molecular orientation Gm data is displayed two-dimensionally in a plane, but the vector representing the actual molecular orientation is a vector in a three-dimensional space, and the molecular orientation Gm data Are also acquired as data in such a three-dimensional space. Here, what is important is that each data (Ec, Gm) of the molded product is acquired so as to have a data value at the same point in the molded product, and the coordinate values of the spatial coordinates set in the molded product are mutually connected. It is related. If there is no data corresponding to each other, the data may be supplemented by interpolation.

(8th step)
In the eighth step (# 3), data of physical property values (for example, linear expansion coefficient Lm and elastic modulus σm) that cannot be directly measured with respect to a molded product molded using the mold 1 is injection-molded specialized for measurement. This is a step of determining the reference sample in association with the acquired data. The reference sample is injection-molded using a reference mold that is a mold specialized for measurement. The reference sample is injection-molded with a reference mold that can form a molded product suitable for measurement, for example, a sheet-shaped molded product, and a resin having the same composition as the resin 2 described above. Similar to the shear strain energy Ec data and molecular orientation Gm distribution data for the molded article described above, the shear strain energy Fc data and the molecular orientation Hm distribution data for this reference sample are numerically calculated and measured, respectively. Obtained by. Further, for this reference sample, data on the linear expansion coefficient Lm and data on the elastic modulus σm are acquired by measurement.

When each of the above data is acquired,
The data for the reference sample (Fc, Hm, Lm, σm)
(Ec, Gm,?,?) Is associated with data on the molded product.
With this mapping,
Data supplemented for the molded product (Ec, Gm, Lm, σm) is acquired.
Here, what is important is that each data (Fc, Hm, Lm, σm) of the reference sample is acquired so as to have a data value at the same point in the reference sample. That is, each data (Fc, Hm, Lm, σm) is data associated with each other by the coordinate value of each point of the spatial coordinates set in the reference sample.

  Next, measurement of the linear expansion coefficient Lm will be described. The same applies to the measurement of the elastic modulus σm. The linear expansion coefficient Lm is measured by an apparatus for thermomechanical analysis (TMA) as a change in elongation of the sample piece with respect to a change in thermal load for a sample piece having a predetermined shape and size cut out from the reference sample. The elongation is not an elongation due to a load, but an elongation due to thermal expansion. From the measured value, the linear expansion coefficient Lm of the part of the reference sample cut out is obtained. Since the linear expansion coefficient Lm of the resin injection molded product has anisotropy due to various factors, the linear expansion coefficient Lm is measured in a plurality of directions of the same part in consideration of the anisotropy. FIG. 9 shows an example in which the measurement results of the linear expansion coefficient Lm in two directions are displayed two-dimensionally in a plane on the test piece TP shown in FIGS. 8 (a) and 8 (b). FIG. 9 shows the results obtained by measuring each linear expansion coefficient Lm in each direction of each point shown in FIG. 9 from each sample piece.

  In actual measurement by thermomechanical analysis, it is necessary to prepare a sample piece having predetermined dimensions required from the thermomechanical analyzer, for example, several cm in length, several mm in width, and 1 mm or less in thickness. As for such a sample piece, it is desirable that the whole sample has a uniform physical property. Sample pieces are used to supplement physical property information that cannot be directly measured in a molded product, and are prepared for various parts having different forms of fluidization and solidification of the resin, and the linear expansion coefficient Lm is obtained for each of the parts. It is desirable. Therefore, the reference sample is composed of a combination of a plurality of types of molded products in which the flow of the resin is a uniform flow structure having a wide layered width, the flow length of the resin is changed, or a branch structure is provided in the resin flow. Sample pieces are provided by being cut from each reference sample. When performing measurement in a plurality of directions of the same part, a plurality of reference samples having the same conditions are prepared. Even when a plurality of reference samples are used, each data (Fc, Hm, Lm, σm) needs to be acquired in association with each other as data of the same point in each reference sample.

  Here, referring to FIGS. 10A and 10B, the (Lm−Hm) relationship between the linear expansion coefficient Lm and the molecular orientation Hm in the reference sample, and the linear expansion coefficient Lm and the shear strain energy Fc. The (Lm-Fc) relationship will be described. In the present embodiment, it is assumed that the same (Lm-Gm) relationship and (Lm-Ec) relationship are established in the molded product.

  As shown in FIG. 10A, there is a correlation between the data of the linear expansion coefficient Lm and the data of the molecular orientation Hm. The curve indicated by MD in the figure is the linear expansion coefficient Lm in the orientation direction of the resin molecules in the injection molding, and the curve indicated by TD is the linear expansion coefficient Lm in the orientation orthogonal direction perpendicular to the orientation direction of the molecules. In injection molding, the resin flow direction MD (see FIG. 3) is usually the orientation direction. The linear expansion coefficient Lm tends to decrease as the degree of molecular orientation increases in the orientation direction, and increases as the degree of molecular orientation increases in the direction perpendicular to the orientation. Further, the linear expansion coefficient Lm in the direction perpendicular to the orientation shows a larger value than the linear expansion coefficient Lm in the orientation direction.

  Further, as shown in FIG. 10B, there is a correlation between the data of the linear expansion coefficient Lm and the data of the shear strain energy Fc that is a temporal integration value of the shear stress generated at the time of resin injection molding. . The increase / decrease in each linear expansion coefficient Lm in the orientation direction and the orientation orthogonal direction with respect to the magnitude of the shear strain energy Fc shows the same tendency as the increase / decrease in each linear expansion coefficient Lm in the orientation direction and the orientation orthogonal direction with respect to the above-described molecular orientation strength. This is because the occurrence of the orientation state in the resin is due to the shear stress generated in the resin during the flow and solidification during molding, and the molecular orientation Hm and the shear strain energy Fc are closely related to each other. It depends on what you are doing. In other words, the data on the molecular orientation Hm and the data on the shear strain energy Fc are considered as complementary data.

  As described above, the data of the linear expansion coefficient Lm can be associated with the data of Ec and Gm using the data of the linear expansion coefficient Lm associated with the data of Fc and Hm. That is, the data of the linear expansion coefficient Lm can be related to the distribution of the shear strain energy Ec and the distribution of the molecular orientation Gm obtained in the sixth step and the seventh step, and the molded product has anisotropy. Data of the linear expansion coefficient Lm can be determined. Similarly, data of elastic modulus σm having anisotropy for a molded product can be determined.

(9th step)
Returning to FIG. 6 and FIG. The ninth step (# 4) is included in the analysis target molded product molded by the mold used for molding the molded product for which the data of Ec and Gm described above are obtained and the resin containing the fibrous filler. This is a process of acquiring data of the three-dimensional orientation Dm of the filler. In the analysis target molded product, the resin of the molded product contains a filler. The filler is, for example, a short fiber made of glass and having a substantially constant diameter. The data of the three-dimensional orientation Dm of the filler can be acquired from, for example, a three-dimensional image of the filler in the injection molded product acquired using X-ray CT. The acquisition is performed by determining the shape and arrangement of each filler in the three-dimensional image. The determination process can be performed, for example, by image processing using a Monte Carlo method in which the shape and arrangement of the model representing the filler are determined at random.

(10th step)
In the 10th step (# 5), based on the data of the linear expansion coefficient Lm determined in the 8th step and the data of the three-dimensional orientation Dm of the filler obtained in the 9th step, the filler is analyzed for the analysis target molded product. This is a step of obtaining data of linear expansion coefficient Lc having anisotropy in consideration by numerical calculation. In this step, similarly to the linear expansion coefficient Lc, data on the elastic modulus σc having anisotropy in consideration of the filler can be obtained for the analysis target molded product.

  This tenth step is executed by numerical calculation using a homogenization method. The homogenization method is a technique for multi-scale analysis that connects a microstructure and a macro structure. By using the homogenization method, a macro average material property can be obtained based on a characteristic displacement which is a response displacement when a macro unit strain is applied to the microstructure. Data of the linear expansion coefficient Lc having anisotropy considering the filler can be obtained by homogenizing the linear expansion coefficient using such a homogenization method. The calculation of the homogenization method can be executed by using a general commercial calculation service, using commercially available software, or using a program. For the calculation of the homogenization method, for example, the Mori-Tanaka model can be used.

  The data of the linear expansion coefficient Lc having anisotropy in consideration of the filler obtained in the tenth step can be mapped to each element of the finite element model for structural analysis of the molded product, and the finite element method model Can be used for structural analysis. The mapping can be performed by a general data mapping method using various existing structural analysis software and tools. By the structural analysis using the finite element method model, the hot warpage of the injection molded product can be obtained by calculating the expansion and contraction generated in each element when the temperature of the molded product is changed. The analysis of the hot warp can be performed by mapping the data of the elastic modulus σc having anisotropy in consideration of the filler in the molded product in the same manner as the data of the linear expansion coefficient Lc or by combining both data.

  According to the present embodiment, data on linear expansion coefficient Lc and elastic modulus σc having anisotropy in consideration of filler in the molded product can be obtained based on the analysis of the flow solidification behavior of the resin. Thus, warpage analysis of the molded product can be performed with high accuracy. In this embodiment, the linear expansion coefficient Lc and the elastic modulus σc are data obtained by locally calculating or measuring the shear strain energy Ec, Fc, molecular orientation Gm, Hm, and filler 3 It is important to be based on data such as the dimensional orientation Dm and the linear expansion coefficient Lm. That is, since each data in this embodiment is based on local data, even if it is a thin molded product or a small-sized molded product that cannot be subjected to hot warp analysis by the conventional method, the necessary data Can be obtained, and hot warpage analysis can be performed with high accuracy. In other words, according to the present embodiment, whether it is an opaque resin or mold, thin molding or high speed phenomenon, solidification such as temperature distribution analysis adapted to real time change of solidification phenomenon based on actual measurement values The behavior analysis can be performed, and further, the warpage analysis of the molded product can be performed.

(Modification)
In this modified example, in the analysis method shown in FIGS. 6 and 7, the mold in the first process is changed to an arbitrary mold, and the sixth to tenth processes are performed. According to this modification, it is possible to obtain the linear expansion coefficient Lc and the elastic modulus σc having anisotropy in consideration of the filler for the analysis target molded product molded using an arbitrary mold. Further, using such a linear expansion coefficient Lc and elastic modulus σc, warpage analysis of the analysis target molded product can be performed.

(Example)
11 to 17 show an embodiment. FIG. 11 shows the measurement results of the change with time of the capacitance Cm (t) of the resin cooled in the mold at five different measurement frequencies, that is, 1, 2, 3, 4, and 5 kHz. The higher the measurement frequency, the denser the time interval in the time axis direction and the higher the time resolution. Conversely, the lower the measurement frequency, the smaller the interval between the measurement points and the lower the time resolution. FIG. 12 shows the measurement frequency dependence of the measured value of the relative dielectric constant of the resin. The higher the measurement frequency, the smaller the relative dielectric constant εr is measured and the measurement sensitivity becomes lower, the signal-to-noise ratio (S / N ratio) decreases, and conversely, the lower the measurement frequency, the larger the relative dielectric constant εr. Measurement sensitivity is increased and the S / N ratio is improved.

  The capacitance Cm (t) has the same measurement frequency dependency as the relative dielectric constant εr of FIG. Therefore, the time resolution and the measurement sensitivity in the measurement of the capacitance Cm (t) are in a trade-off relationship with respect to the measurement frequency. Therefore, in the following measurement example of the capacitance Cm (t), the measurement frequency was fixed to 5 kHz from the viewpoint of ensuring time resolution.

  FIG. 13 shows the change over time in the capacitance of the resin that is cooled and solidified in the mold under a fixed molding condition (injection resin temperature 370 ° C., mold temperature 95 ° C.), and the number of samples n = 5. The results of five measurements are shown. 14, 15, and 16 show other constant molding conditions, that is, FIG. 14 (injection resin temperature 400 ° C., mold temperature 95 ° C.) and FIG. 15 (injection resin temperature 370 ° C., mold temperature). 75 ° C.) and FIG. 16 (injection resin temperature 400 ° C., mold temperature 75 ° C.).

  The result of FIG. 14 with respect to FIG. 13 is a result of the molding conditions in which the mold temperature is the same and the injection resin temperature is increased by 30 ° C., and the injection resin temperature is high as shown in FIG. As a result, a large measured capacitance value (see the peak value) is obtained. The same applies to the result of FIG. 16 with respect to FIG. That is, a difference in molding conditions of 30 ° C. can be detected in the measured capacitance value.

  FIG. 13 and FIG. 15 (the same applies to FIG. 14 and FIG. 16) are the measurement results under the molding conditions where the injection resin temperature is the same and the mold temperature is 20 ° C., but the capacitance Cm (t) is measured. The effect of mold temperature variation on the results is less clear than the effect of injection resin temperature. This is because although the mold temperature affects the surface layer portion of the resin in contact with the mold, it has little or no effect on the entire resin contributing to the capacitance Cm (t). Conceivable.

  In the measurement as described above, the number of samples n is increased, the measurement frequency is optimized, the average value of the measurement results is obtained, and the time-dependent waveform of the capacitance Cm (t), that is, the change with time. Is determined and compared with the calculated capacitance Cc (i, t). In order to improve the measurement, for example, it is important to ensure measurement conditions that can capture the rising peak of the capacitance Cm (t).

  The present invention is not limited to the above-described configuration, and various modifications can be made. For example, the configurations of the above-described embodiments can be combined with each other.

1 Mold 2 Resin 3 Counter electrode Cc (i, t) Capacitance Cm (t) Capacitance Dm Filler three-dimensional orientation Ec Shear strain energy (for molded product)
Fc shear strain energy (of reference sample)
Gm molecular orientation (for molded products)
Hm molecular orientation (of reference sample)
J (i) Calculation condition Lm Linear expansion coefficient (of reference sample)
Lc Linear expansion coefficient (for the molded product to be analyzed)
T (i, t), T (x, t) Temperature distribution ε (T) Dielectric constant ε (i, t) Dielectric constant distribution σm Elastic modulus σc Elastic modulus (of the object to be analyzed)

Claims (6)

In the analysis method of the flow solidification behavior of the resin in the mold in injection molding,
A first step of injecting resin into a dielectric mold having a counter electrode to perform injection molding, and measuring a change with time in capacitance between the counter electrodes;
A second step of modeling the mold of the first step and numerically calculating the change over time of the temperature distribution in the die due to the fluidized solidification behavior of the resin;
A third step of converting the temperature distribution in the mold at each time obtained in the second step into a dielectric constant distribution using data on the temperature dependence of the dielectric constant of the resin;
A fourth step in which the time-dependent change in capacitance between the counter electrodes is obtained by numerical calculation using the dielectric constant distribution converted in the third step;
The time scale of the second step in which the capacitance of the first step and the capacitance of the fourth step are equal is obtained, and the temperature distribution of the second step on the time scale is determined as the mold on the real time scale. And a fifth step of changing the temperature distribution of the resin over time. A method for analyzing the fluidization and solidification behavior of the resin.   The method for analyzing the fluidization and solidification behavior of the resin according to claim 1, wherein in the second step, the time scale is changed by changing a heat transfer coefficient of the wall surface of the mold. In the first step, the capacitance is measured by impedance measurement performed by applying an AC voltage between the counter electrodes, and the time resolution of the measurement is determined with respect to the speed of change of the measured capacitance with time. If insufficient, measure with higher frequency AC voltage,
The analysis of the flow solidification behavior of the resin according to claim 1 or 2, wherein the third step uses temperature dependency data of a dielectric constant depending on a frequency used in the measurement of the first step. Method. In the first step, when the capacitance is measured by impedance measurement performed by applying an AC voltage between the counter electrodes, and the signal level of the measured capacitance is insufficient, an AC having a lower frequency is used. Measured using voltage,
The analysis of the flow solidification behavior of the resin according to claim 1 or 2, wherein the third step uses temperature dependency data of a dielectric constant depending on a frequency used in the measurement of the first step. Method. The distribution of the shear strain energy, which is an integrated value of the shear stress acting on the resin molded in the mold, is numerically calculated on the time scale that gives the temporal change of the temperature distribution determined in the fifth step. A sixth step determined by calculation;
For a molded product molded using the mold, a seventh step for determining the distribution of molecular orientation of the resin in the molded product by measurement;
Calculated shear strain energy data obtained from a reference sample molded using a reference mold and the resin, measured molecular orientation data, and anisotropy associated with these data Using the data of the measured values of the linear expansion coefficient or elastic modulus, the distribution of the shear strain energy obtained by the sixth step and the distribution of the molecular orientation obtained by the seventh step An eighth step of determining linear expansion coefficient or elastic modulus data having anisotropy for the molded article by associating modulus data;
A ninth step of acquiring data of the three-dimensional orientation of the filler in the analysis target molded product formed using the mold of the first step including a fibrous filler in the resin;
Using the linear expansion coefficient or the elastic modulus data determined in the eighth step and the three-dimensional orientation data of the filler obtained in the ninth step, the analysis target molded product is considered different from the filler. And a tenth step of obtaining data of linear expansion coefficient or elastic modulus having anisotropy by numerical calculation, wherein the flow solidification behavior of the resin according to any one of claims 1 to 4 is provided. analysis method.   Anisotropy in which fillers are taken into account for the molded object to be analyzed molded by the arbitrary mold by performing the sixth to tenth processes using an arbitrary mold instead of the mold of the first process 6. A method for analyzing the fluidization and solidification behavior of a resin according to claim 5, wherein data of a linear expansion coefficient or elastic modulus having a property is obtained.

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