JP4779863B2 - Injection molding simulation computer, etc. - Google Patents

Description

The present invention relates to a simulation technique for injection molding .

The matters which become the background of the present invention are listed below.
(1) Injection molding of a molded product is widely performed by filling a mold having a cavity with a molten material (for example, molten resin). For example, automobile bumpers and instrument panels are formed by injection molding.
(2) The injection molded product has a front surface and a back surface. For example, when a bumper or an instrument panel is assembled in an automobile, those injection molded products have a surface that can be visually recognized and a surface that cannot be visually recognized. The surface that can be visually recognized is the surface of the injection molded product, and the surface that cannot be visually recognized is the back surface of the injection molded product.
(3) Many materials used for injection molding shrink when solidified. When the molten material filled in the cavity contracts in the process of solidifying, the outer shape surface of the molded product is separated from the molding surface forming the cavity, and the outer shape of the molded product cannot be formed into the intended shape.
(4) The surface of the molded product needs to be finished in the intended shape. On the other hand, the shape of the back surface of the molded product is less important than the surface of the molded product. Patent Document 1 below discloses a technique for finishing the surface of a molded product into an intended shape. In this technique, a pressurized fluid (for example, air) is injected into the back side of the material in the cavity after the molten material is filled into the cavity and before the material is completely solidified. When pressurized fluid is injected into the back side of the material, the back side separates from the mold before the surface of the material. Since the material shrinks in a state where the surface does not separate from the mold, the surface of the molded product can be finished in the intended shape. In this case, since the back surface of the molded product is molded away from the mold, the back surface of the molded product deviates from the shape of the cavity. However, since the shape of the back surface of the molded product is not emphasized, it does not matter if the back surface of the molded product deviates from the cavity shape.

(5) The inventors of the present invention want to injection-mold a molded product having a curved portion with the back surface inside. FIG. 1 shows an example of a molded product having a curvature portion with the back surface inside. The molded product 10 has a front surface 12 and a back surface 14. The molded product 10 has a curvature portion 16 with the back surface 14 on the inside.
FIG. 2 simply shows an apparatus 20 for injection molding the molded article 10. The injection molding apparatus 20 has a molding die 22. The molding die 22 has an upper die 22a and a lower die 22b. A cavity 24 is formed between the upper mold 22a and the lower mold 22b. The upper mold 22a has a filling port 26 for molten material. The filling port 26 opens at a position corresponding to the surface 12 of the molded article 10. The lower mold 22b has an inlet 28 for pressurized fluid. The inlet 28 opens at a position corresponding to the back surface 14 of the molded product 10.
(6) FIG. 3 shows the state immediately after the cavity 24 is filled with the molten material. In the molten material filled in the cavity 24, the portion 10 a in contact with the mold 22 is solidified first, and the portion 10 b far from the mold 22 is solidified later. In this specification, the material in which the solidified portion 10a and the non-solidified portion 10b are formed is referred to as “semi-solidified material”.
When the filling of the molten material is completed, the molten material is continuously added from the filling port 26 into the cavity 24 in order to compensate for the shrinkage of the material in the cavity 24. Continuing to add the molten material after the cavity 24 is filled with the molten material is called “holding pressure”.

(7) Pressurized fluid is injected from the inlet 28 while filling the molten material and / or during holding pressure. At this time, the material in the cavity 24 is in a semi-solid state. A pressurized fluid is injected toward the back surface 14 of the semi-solidified material 10. If the pressure of the pressurized fluid is too small, the pressurized fluid does not spread between the back surface 14 of the material 10 and the mold 22, and it is not guaranteed that the back surface 14 peels from the mold 22 before the front surface 12. If the pressure of the pressurized fluid is increased sufficiently, it is ensured that the back surface 14 of the material 10 peels from the mold 22 before the front surface 12, but a device (eg, a pump) for supplying the pressurized fluid is provided. It will increase in size. The inventors wish to inject the pressurized fluid at a minimum pressure that ensures that the back surface 14 of the material 10 peels away from the mold 22 prior to the front surface 12.
(8) When pouring (filling or holding pressure) a molten material from the filling port 26, the injection pressure (filling pressure or holding pressure) acts on the material 10 in the cavity 24. If the flow analysis of the material is executed using a computer, the magnitude (vector) of the force acting on each position (each position in the cavity 24) of the semi-solidified material 10 due to the injection of the molten material. Can be analyzed. In the flow analysis, the shape of the molded product 10 (that is, the shape of the cavity 24) is divided into a plurality of minute elements. In the present specification, this minute element is referred to as a “finite element”.
FIG. 4 shows a diagram in which a part of the molded product 10 is divided into a plurality of finite elements m. In practice, all parts of the molded product 10 are divided into finite elements m. If the flow analysis is executed, a force vector acting on each finite element m due to the injection of the molten material can be obtained. This force vector changes over time under the influence of the filling pressure of the molten material, the holding pressure, the solidification state of the material, and the like. In the present specification, a force vector acting on one finite element m due to injection of a molten material is referred to as an “injection-induced force vector”.
JP 2005-349683 A

In the present specification, each finite element m constituting the back surface 14 of the molded product 10 is referred to as a “back surface side finite element mr”. From the injection-induced force vector obtained for each back surface side finite element mr, the magnitude of the force that each back surface side finite element mr applies perpendicularly to the mold 22 can be obtained. In this specification, the force that one back side finite element mr applies to the mold 22 in the vertical direction due to the injection of the molten material is referred to as “injection-induced normal force”.
In order for the pressurized fluid to spread between the back surface 14 of the semi-solidified material 10 and the mold 22, the pressurized fluid having a magnitude exceeding the vertical force resulting from the injection of each finite element mr on the back surface side. I thought I should inject. For example, if the largest injection-induced normal force among all the back surface side finite elements mr at a predetermined timing is P, if a pressurized fluid slightly larger than P is injected, the semi-solid state at the above predetermined timing It was thought that the pressurized fluid could spread over the entire back surface 14 of the material 10.
However, when the molded product 10 having the curved portion 16 with the back surface inside is injection-molded, even if the pressurized fluid of the size obtained by the above method is sent to the back surface 14 of the material 10, it is added to the cavity 24. It has been found that an event in which no pressurized fluid enters, or an event in which the pressurized fluid does not spread over the entire back surface 14 of the material 10 even when the pressurized fluid enters the cavity 24 occurs.

  The present invention has been made in view of the above circumstances, and in the case of injection molding of a molded product having a curved portion with the back surface inside, a pressurized fluid between the back surface of the semi-solidified material and the mold Provide a technique capable of knowing the magnitude of the fluid pressure required for the pressure to spread.

As a result of repeated research, the present inventors have found that the following phenomenon occurs when a molded product having a curvature portion with the back surface inside is injection molded.
The solid line in FIG. 5 shows the semi-solidified material 10 present in the cavity 24. The material 10 in the cavity 24 tends to deform in the direction of arrow D1 as it solidifies. That is, the material 10 tends to be deformed so as to wrap around the back surface 14 side. There are several possible reasons for this event. (1) Material shrinkage during the solidification process. (2) A difference in solidification speed in which the molten material close to the mold is solidified first, and the molten material far from the mold is solidified later. (3) Residual stress of solidified material.
Even if the semi-solidified material 10 is deformed in the direction of the arrow D1, it cannot be freely deformed because it is accommodated in the mold 22. In this case, the back surface 14 of the material 10 pushes the mold 22 due to the material 10 attempting to deform in the direction of the arrow D1. That is, there is a force that the back surface 14 of the material 10 applies to the mold 22 due to the material 10 trying to deform. In this specification, the force that one back side finite element mr applies to the mold 22 in the vertical direction due to the semi-solidified material 10 being deformed is referred to as “deformation-induced normal force”. Call it. In FIG. 5, six types of deformation-induced normal forces PL <b> 1 to PL <b> 6 are shown assuming that there are six back side finite elements mr. The present inventors have found that the phenomenon that the pressurized fluid does not spread between the back surface 14 of the material 10 and the mold 22 is caused by the deformation-induced normal forces PL1 to PL6. Only when both the injection-induced normal force and the deformation-induced normal force acting on the material 10 are taken into account, the fluid pressure required for the pressurized fluid to spread between the back surface 14 of the material 10 and the mold 22 can be determined. .

The simulation computer according to the present invention performs a semi-molding operation in a cavity when the molded product is injection-molded by filling a molten mold into a molding die having a cavity for molding an injection-molded product having a curved portion with a back surface on the inside. Due to the fact that the solidified material is about to deform, the force that the back surface applies to the mold is calculated.
The simulation computer includes a basic data file, a flow analysis device, a flow analysis result data file, a deformation analysis device, a deformation analysis result data file, a stiffness data file, and a stiffness analysis device.
The basic data file stores basic data for flow analysis. Basic data includes any data that one skilled in the art would need for flow analysis. Generally, the basic data file stores cavity shape data, material property data, and injection condition data. The basic data file may not store the data exemplified above. The basic data file may store data other than the data exemplified above. For example, the basic data file may store mold temperature distribution data.

The flow analysis device executes flow analysis of a material in a cavity using basic data stored in a basic data file. The flow analysis can be executed using various known flow analysis software. In the flow analysis, data necessary for performing the deformation analysis described later is calculated. The data calculated by the flow analysis includes any data that those skilled in the art think necessary for deformation analysis. For example, the flow analysis device may calculate a change with time of the injection-causing force vector of each finite element. Further, for example, the flow analysis device may calculate a change with time of the temperature of each finite element.
For example, the flow analysis apparatus may perform flow analysis from the start of filling of the molten material to the opening of the mold. On the other hand, the flow analysis device may perform flow analysis for a period required for deformation analysis described later and may not perform flow analysis for other periods. For example, the flow analysis device may perform flow analysis from the start of filling of the molten material to a predetermined timing described later.
Note that the term “finite element” in this specification is to be interpreted in the broadest sense and includes finite elements used in various known analysis methods. In the present invention, for example, a solid finite element or a shell finite element may be used.
The flow analysis result data file stores the flow analysis result obtained by the flow analysis device.

The deformation analysis apparatus executes deformation analysis of a semi-solidified material at least at a predetermined timing using the flow analysis result stored in the flow analysis result data file.
The above “predetermined timing” is a timing at which the user thinks that the pressurized fluid is desired to spread between the back surface of the material and the mold, and can be arbitrarily set by the user. As will be described later, deformation analysis of a semi-solidified material may be executed for each of a plurality of timings.
The deformation analysis can be executed using various known deformation analysis software. In the deformation analysis, data necessary for performing a stiffness analysis described later is calculated. The data calculated by the deformation analysis includes any data that those skilled in the art think necessary for the stiffness analysis.
The content of the deformation analysis will be described with reference to FIG. As described above, the material 10 tends to be deformed in the direction of the arrow D1 in the process of solidifying, but cannot be deformed because the mold 22 exists. That is, the material 10 retains the solid line shape. If the molding die 22 is opened at this time and the material 10 is taken out, the material 10 is deformed in the direction of the arrow D1. The broken line in FIG. 5 shows the material 10 after deformation. When the deformation analysis is executed, it can be said that the shape of the deformed material (the broken line shape in FIG. 5) when the material 10 is freely deformed at the predetermined timing can be obtained. Hereinafter, the description will be continued assuming that the shape of the material after the deformation is obtained by the deformation analysis. This is because it is easy to understand the contents of the stiffness analysis described later. However, in the deformation analysis, any format of data may be obtained as long as it is in a format that can be used for stiffness analysis described later. For example, in the deformation analysis, the volume shrinkage rate (the degree and direction of shrinkage) of each finite element m when the material 10 is freely deformed at the predetermined timing may be obtained.
The deformation analysis result data file stores a deformation analysis result obtained by the deformation analysis apparatus.

The stiffness data file stores material stiffness data. It can be said that the stiffness data is data defining the relationship between stress and strain applied to the material. It can also be said that the rigidity data is data defining the relationship between the load applied to the material and the amount of deformation. The stiffness data stored in the stiffness data file is used in stiffness analysis described later.
It is preferable that the rigidity data of the material at the predetermined timing (that is, the semi-solidified material) is used. However, instead of using the stiffness data of the semi-solidified material, the stiffness data of the fully solidified material may be used. In this case, the stiffness data file stores stiffness data in a state where the material is completely solidified. Even in this case, the present inventors have confirmed that a considerably accurate rigidity analysis result can be obtained.

The content of the stiffness analysis will be described with reference to FIG. The stiffness analysis can be executed using various known stiffness analysis software.
The deformation analysis result data file stores the shape data (deformation analysis result) of the material 10 indicated by a broken line. The stiffness analysis apparatus uses the deformation analysis result stored in the deformation analysis result data file and the stiffness data stored in the stiffness data file. Further, the stiffness analysis apparatus uses a condition for constraining the material 10 in the cavity 24. That is, the condition that the material 10 is restrained at the position of the solid line in FIG. 5 is used. The stiffness analysis apparatus executes the stiffness analysis using the deformation analysis result, the stiffness data, and the constraint condition, thereby causing the semi-solidified material 10 at the predetermined timing to be deformed. The force applied to the mold 22 by the back surface 14 of 10 can be calculated. This is easy to understand when considered as follows.
The magnitude of the force (hereinafter referred to as “returning force”) required to return the material 10 existing at the position of the broken line in FIG. 5 to the position of the solid line can be obtained from the rigidity data. The rigidity analysis is performed on each back surface side finite element mr constituting the back surface 14 of the material 10 when a force opposite to the above return force is applied to the material 10 under the condition of constraining the material 10 at the position of the solid line. It is easy to understand if it is considered to calculate an acting force vector. This force vector can be said to be a force vector acting on one back side finite element mr due to the deformation of the semi-solidified material 10 at the predetermined timing. In this specification, this force vector is referred to as a “deformation-induced force vector”. If the deformation-induced force vector of each back surface side finite element mr is known, the forces (PL1 to PL6 in the example of FIG. 5) that each back surface side finite element mr applies to the mold 22 in the vertical direction can be obtained. When the rigidity analysis is executed using the deformation analysis result, the rigidity data, and the constraint condition, the deformation-induced normal forces PL1 to PL6 can be obtained.

The stiffness analyzer calculates the force that the back surface applies to the mold due to the semi-solid state material attempting to deform at the predetermined timing. The “force” calculated by the stiffness analyzer is preferably a deformation-induced normal force, but may be a deformation-induced force vector. This is because if the deformation-induced force vector is known, the deformation-induced normal force can be obtained.
Further, the stiffness analysis apparatus may calculate a deformation-induced normal force (or a deformation-induced force vector) for each of all the back surface side finite elements. On the other hand, the stiffness analyzer may calculate the deformation-induced normal force (or deformation-induced force vector) for only a part (one or a plurality of back-side finite elements) of all the back-side finite elements. For example, the deformation-induced normal force is expected to be relatively large at the curvature portion of the semi-solidified material. For this reason, the deformation-induced normal force (or deformation-induced force vector) may be calculated only for each back surface side finite element constituting the back surface of the curvature portion. Alternatively, the deformation-induced normal force (or deformation-induced force vector) may be calculated for only one back surface side finite element constituting the back surface of the curvature portion. All of these correspond to “calculating the force that the back surface applies to the mold due to the semi-solidified material being deformed”.
Further, the stiffness analysis apparatus does not have to calculate the stiffness analysis result in units of finite elements. For example, for a unit portion (for example, a curvature portion) larger than the finite element, the force applied to the mold by the back surface of the portion may be calculated. This may be obtained by calculating the deformation-induced normal force of each back surface side finite element constituting the back surface of the portion and calculating the average thereof.

According to the computer of the present invention, the force that the back surface applies to the mold due to the semi-solid material being deformed in the cavity (for example, in the example of FIG. 5, the deformation-induced normal forces PL1 to PL6). Can be calculated. By taking into account the deformation-induced normal forces PL1 to PL6, the magnitude of the fluid pressure required for the pressurized fluid to spread between the back surface of the semi-solidified material and the mold can be accurately obtained.
The computer executes flow analysis, deformation analysis, and stiffness analysis. Since any analysis method is known, it may seem that the above computer is merely a combination of a plurality of known analyses. However, conventionally, the deformation analysis is performed after the material is completely solidified in the cavity, thereby analyzing how the fully solidified material deforms after opening the mold. In contrast, in the present invention, deformation analysis of a semi-solidified material is performed. Further, the force applied to the mold by the back surface of the semi-solidified material is calculated by executing the rigidity analysis using the deformation analysis result. This is a novel technical idea created by the present inventors, and is not simply a combination of known analysis methods.

  In addition, it is preferable that said computer has an apparatus which outputs the rigidity analysis result calculated by the rigidity analysis apparatus. Here, “output” includes displaying the stiffness analysis result, transmitting the stiffness analysis result to another device, and the like. Here, “displaying” or “transmitting” includes displaying or transmitting the calculation result by using the rigidity analysis result for another calculation.

The rigidity analysis apparatus is configured to cause the back surface of the semi-solidified material to be deformed at the predetermined timing with respect to each of the plurality of back surface side finite elements constituting the back surface of the semi-solid state material. The force applied by the side finite element in the direction perpendicular to the mold may be calculated. In other words, the stiffness analyzer may calculate the deformation-induced normal force of each back surface side finite element at the predetermined timing.
The back side finite element may be a solid finite element or a shell finite element.

The above computer stores the stiffness analysis result data file storing the stiffness analysis results obtained by the stiffness analyzer, and the flow analysis result and stiffness analysis result data file stored in the flow analysis result data file. There may be further provided an arithmetic device for calculating using the rigidity analysis result.
In this case, the flow analysis device, for each of the plurality of back surface side finite elements constituting the back surface of the semi-solidified material, the back surface side finite element is caused by material filling or holding pressure at the predetermined timing. A force applied in a direction perpendicular to the mold may be calculated. That is, the flow analysis device may calculate the injection-induced normal force of each back surface side finite element at the predetermined timing.
For each of the plurality of back surface side finite elements constituting the back surface of the semi-solidified material, the arithmetic unit causes the back surface side finite element to be formed on the mold due to the filling or holding pressure of the material at the predetermined timing. The force applied in the vertical direction (injection-induced vertical force) and the back-side finite element applied in the vertical direction with respect to the mold due to the semi-solidified material attempting to deform at the predetermined timing. The sum of forces (deformation-induced vertical forces) may be calculated.
For example, when the injection-induced normal force of the back surface side finite element mr1 at the predetermined timing is PT1 and the deformation-induced normal force is PL1, the sum of PT1 and PL1 is calculated. Also for each of the other back surface side finite elements mr, the sum of the injection-induced normal force and the deformation-induced normal force is calculated. When pressurized fluid exceeding the calculation result of each back side finite element (sum of injection-induced normal force and deformation-induced normal force) is injected, it is between the back surface of the semi-solidified material and the mold at the predetermined timing described above. The pressurized fluid can spread.
According to this configuration, the magnitude of the required fluid pressure can be calculated with high accuracy.

A method of injection molding using the above calculation results is useful. That is, this injection molding method is obtained by a step of filling a mold having a cavity corresponding to a molded product having a curved portion with the back surface inside, and the arithmetic unit of the above-described injection molding simulation computer. And a step of injecting a pressurized fluid exceeding each value into the back side of the semi-solidified material at the same time as or before the predetermined timing.
The above “beyond each value obtained by the arithmetic device” includes adopting the same numerical value as the maximum value obtained by the arithmetic device.
When this injection molding method is used, the pressurized fluid can spread between the back surface of the semi-solidified material and the mold at the predetermined timing. It is guaranteed that the back surface peels from the mold before the surface of the molded product. For this reason, the surface of the molded product can be finished in the intended shape.

The stiffness analyzer may calculate the deformation-induced normal force (or the deformation-induced force vector) at the predetermined timing for each of all the back surface side finite elements. On the other hand, the stiffness analyzer may calculate a deformation-induced normal force (or a deformation-induced force vector) for only a part of the back surface side finite elements. For example, the deformation-induced normal force tends to increase on the back surface of the curved portion of the semi-solidified material as compared with other portions. For this reason, the back surface of the curvature portion has a larger sum of the deformation-induced normal force and the injection-induced normal force (hereinafter referred to as “calculation result”) than the other portions. When it is expected that the calculation result of the back surface side finite element constituting the curvature part in each back surface side finite element is expected to be the maximum, the calculation result may be obtained for the back surface of the curvature part, and the calculation result of the other part is obtained. There is no need to ask. For this reason, the rigidity analysis apparatus tries to deform the semi-solidified material at the predetermined timing with respect to only at least one back surface side finite element constituting the back surface of the curvature portion of the semi-solid material. Therefore, the force applied to the mold by the back surface side finite element may be calculated.
In this case, the deformation-induced normal force (or deformation-induced force vector) is not calculated for the other back surface side finite elements. The amount of computer calculation can be reduced.

If the timing at which the pressurized fluid is desired to spread between the back surface of the material and the mold is known, only the stiffness analysis result at that timing needs to be obtained. However, when the timing is not known, the deformation analysis apparatus and the rigidity analysis apparatus may execute the deformation analysis and the rigidity analysis for each of a plurality of timings.
According to this configuration, a rigidity analysis result at each timing is obtained. The user can determine the timing at which the pressurized fluid is desired to spread between the back surface of the material and the mold in consideration of the rigidity analysis result at each timing.
The period from the start to the end of the “plural timings” can be arbitrarily set. For example, a period from when filling of the material into the cavity to when the mold is opened may be set. Further, for example, a part of the period from the start of filling of the material into the cavity to the opening of the mold may be set. For example, when it is determined that the pressurized fluid is injected during the holding pressure, the period may be set from the start to the end of the holding pressure.

The following method is also useful. In this method, when a molded product is injection-molded by filling a mold having a cavity corresponding to the molded product having a curvature portion with the back surface inside, the material in a semi-solid state in the cavity. This is an injection molding silation method in which the computer calculates the force applied to the mold by the back surface of the mold due to the deformation. In this method, the computer executes the following steps.
(1) A step of creating a basic data file storing basic data for flow analysis. (2) A flow analysis process for performing flow analysis of a material in a cavity using basic data stored in a basic data file.
(3) A step of creating a flow analysis result data file storing the flow analysis results obtained in the flow analysis step.
(4) A deformation analysis step of executing deformation analysis of a semi-solidified material at least at a predetermined timing using the flow analysis result stored in the flow analysis result data file.
(5) A step of creating a deformation analysis result data file storing the deformation analysis result obtained in the deformation analysis step.
(6) A step of creating a stiffness data file storing material stiffness data.
(7) Using the deformation analysis results stored in the deformation analysis result data file, the rigidity data stored in the rigidity data file, and the conditions for constraining the semi-solidified material in the cavity, A stiffness analysis step of calculating the force applied to the mold by the back surface due to the semi-solid state material attempting to deform at a predetermined timing.
By considering the force (rigidity analysis result) calculated by this method, the magnitude of the fluid pressure required for the pressurized fluid to spread between the back surface of the semi-solidified material and the mold is accurately determined. Can be sought.
In addition, the computer program which makes a computer perform each said process (1)-(7) is one of the techniques created by the present inventors.

The main features of the techniques described in the examples below are listed.
(Embodiment 1) The molded product whose back surface is the inside is an automobile part.
(Mode 2) The basic data file stores at least cavity shape data, material property data, and injection condition data. The cavity shape data is data obtained by dividing the shape of the cavity (molded product) into a plurality of finite elements. The material property data includes at least one of a material temperature-viscosity property and a material cooling property. The injection condition data includes at least one of injection pressure, injection speed, holding pressure, holding time, and material initial temperature.
(Mode 3) The constraint condition used in the rigidity analysis is a condition that the end of the semi-solidified material is constrained in the cavity.

Embodiments of the present invention will be described with reference to the drawings. In this embodiment, a computer that executes injection molding simulation will be described. Before describing the configuration of this computer, the shape of a molded product to be injection-molded and the configuration of an injection molding apparatus will be described.
FIG. 6 shows a perspective view of the molded product 50 of the present embodiment. The molded product 50 of the present embodiment is an automobile bumper. The molded product 50 has a front surface 52 and a back surface 54. The surface 52 is a surface that can be visually recognized when the molded product 50 is assembled to the automobile body. The back surface 54 is a surface that cannot be visually recognized even when the molded product 50 is assembled to the automobile body. The molded product 50 has two curvature portions 56 and 58 in which the back surface 54 is inside (valley).

FIG. 7 shows an injection molding apparatus 70 for the molded product 50. The injection molding apparatus 70 includes a molding die 72, a plunger 78, a pump 82, and the like.
The molding die 72 has an upper die 72a and a lower die 72b. A cavity 74 is formed between the upper mold 72a and the lower mold 72b. The cavity 74 has a shape corresponding to the molded product 50. The upper mold 72 a has a gate 76. One end of the gate 76 opens into the cavity 74. One end of the gate 76 opens at a position corresponding to the surface 52 of the molded product 50. The other end of the gate 76 communicates with the plunger 78. The lower mold 72 b has an air injection path 80. One end of the air injection path 80 opens into the cavity 74. One end of the air injection path 80 opens at a position corresponding to the back surface 54 of the molded product 50. The other end of the air injection path 80 communicates with the pump 82.
The plunger 78 injects molten resin into the gate 76. Various injection conditions can be set for the plunger 78. For example, an injection pressure, an injection speed, an injection time, a holding pressure, a holding time, and the like can be set. The plunger 78 injects molten resin according to the set injection conditions. The molten resin injected into the gate 76 from the plunger 78 is filled in the cavity 74.
The pump 82 injects pressurized air into the air injection path 80. Various air injection conditions can be set for the pump 82. For example, air injection timing, air injection time, air pressure, etc. can be set. The pump 82 injects air according to the set air injection conditions. The air injected from the pump 82 into the air injection path 80 spreads between the back surface 54 of the molded product (semi-solidified resin) 50 in the cavity 72 and the molding die 72.

FIG. 8 shows a time chart of each process executed by the injection molding apparatus 70. The injection molding apparatus 70 performs a filling process in which the molten resin is filled into the cavity 74 by the plunger 78. When the cavity 74 is filled with the molten resin, the filling process ends.
When the filling process is completed, the injection molding apparatus 70 performs a pressure holding process in which the resin is continuously injected from the plunger 78.
The injection molding apparatus 70 can start the air injection process during the pressure holding process (G1 in FIG. 8). The air injection process may be started simultaneously with the start of the pressure holding process (G2 in FIG. 8). Further, the air injection step may be started before starting the pressure holding step (during the filling step) (G3 in FIG. 8). The air injection process may be started at any timing within the range of the arrow tr in FIG. In the following description, it is assumed that the air injection process is started at the timing indicated by the symbol ts in FIG. That is, description will be made assuming that the air injection step indicated by the arrow G1 in FIG. 8 is performed.
When the air injection process is completed, the upper mold 72a and the lower mold 72b are opened, and the molded product 50 is taken out.

Then, the structure of the injection molding simulation computer of a present Example is demonstrated. FIG. 9 shows functions realized by the computer 100. Although not shown, the computer 100 has hardware such as a CPU, a ROM, and a RAM. The computer 100 stores a program (software) for executing each analysis and calculation described below. The computer 100 realizes each function illustrated in FIG. 9 by the hardware and the program operating in cooperation.
The computer 100 includes an input device 102, a plurality of analysis devices 104, 106, 108, an arithmetic device 110, an output device 112, and a plurality of data files 120, 122, 124, 126, 128, 130.
The input device 102 is, for example, a keyboard or a mouse. The input device 102 is operated by a user. The user can input various data using the input device 102.
Each analysis device 104, 106, 108 performs various analyses. The contents of the analysis performed by each analysis device 104, 106, 108 will be described in detail later. The arithmetic device 110 performs arithmetic processing based on the data obtained by the analysis devices 104 and 108. The contents of the calculation executed by the calculation device 110 will be described in detail later.
The output device 112 displays the data obtained by the analysis device 108 and the data obtained by the arithmetic device 110.

The contents of the data stored in each data file 120, 122, etc. and the contents of the analysis executed using the data will be described in order.
The basic data file 120 stores basic data necessary for flow analysis. The user can input basic data using the input device 102. The computer 100 creates a basic data file 120 that stores the input basic data. The basic data file 120 of this embodiment stores cavity shape data, material property data, injection condition data, and mold temperature distribution data.

The cavity shape data is data defining the shape of the cavity 74 (that is, the shape of the molded product). The cavity shape data of this embodiment is obtained by dividing three-dimensional CAD data into a plurality of finite elements. FIG. 10 shows the cavity shape data. The molded product 50 (cavity 74) is divided into a plurality of finite elements m (mf, mr).
In the cavity shape data of this embodiment, the molded product 50 is divided into two finite elements m in the thickness direction. However, the cavity shape data may be obtained by dividing the molded product 50 into three or more finite elements m in the thickness direction. The cavity shape data may be configured by only one finite element m in the thickness direction.
The molded product 50 has a plurality of finite elements mf constituting the front surface 52 and a plurality of finite elements mr constituting the back surface 54. Hereinafter, the finite element mf is referred to as “front-side finite element mf”, and the finite element mr is referred to as “back-side finite element mr”.

  The material property data is data that defines the property of the material (that is, resin). The material property data of this example includes the temperature-viscosity property and cooling property of the resin. The temperature-viscosity characteristic is data defining the relationship between the temperature and viscosity of a resin. Usually, a temperature-viscosity curve is used. The cooling characteristic is data defining the ease of cooling of the resin.

  The injection condition data is data that defines the injection conditions when the resin is injected into the cavity 74. The injection condition data of this embodiment includes an injection pressure, an injection speed, a holding pressure, a holding time, and an initial resin temperature. The injection pressure is the pressure of the resin injected from the plunger 78 in the filling process. The injection speed is the injection speed of the resin injected from the plunger 78 in the filling process. The holding pressure is a pressure applied to the resin in the cavity 74 from the plunger 78 in the holding step. The pressure holding time is the duration of the pressure holding process. The resin initial temperature is an initial temperature of the resin injected from the plunger 78.

  The mold temperature distribution data is data that defines the temperature distribution of the mold 72. A cooling water passage (not shown) is formed inside the mold 72. For this reason, as for the shaping | molding die 72, the part near a cooling water path | route is low temperature, and the part far from a cooling water path | route is high temperature. A temperature difference is formed inside the mold 72, and this information is stored as mold temperature distribution data.

The flow analysis device 104 functions by operating flow analysis software. The flow analysis software of this embodiment is “3D-TIMON-AWARP”, which is a highly accurate warped deformation version of 3D-TIMON (Toray Engineering Co., Ltd.).
The flow analysis device 104 uses the basic data stored in the basic data file 120 to execute the flow analysis of the resin in the cavity 74. The flow analyzer 104 is a force vector (injection-induced force vector) that acts on each finite element m due to resin filling or holding pressure at each timing from the start of the filling process to the end of the holding pressure process. Is calculated. That is, the flow analysis device 104 calculates the change over time of the injection-causing force vector of each finite element m. Further, the flow analysis device 104 calculates the temperature of each finite element m at each timing from the start of the filling process to the end of the pressure holding process. That is, the flow analysis device 104 calculates a change with time of the temperature of each finite element m.

The flow analysis result data file 122 illustrated in FIG. 9 stores the flow analysis result calculated by the flow analysis device 104. FIG. 11 shows an example of the stored contents of the flow analysis result data file 122. The flow analysis result data file 122 stores a change with time of the injection cause force vector of each finite element m and a change with time of the temperature T of each finite element m. For example, at the timing ts, the injection-induced force vector of the back side finite element mrx is Arx (ts), and the temperature is Trx (ts).
The flow analysis result stored in the flow analysis result data file 122 is used in the deformation analysis described below.

The deformation analysis apparatus 106 shown in FIG. 9 functions by operating deformation analysis software. The flow analysis software TIMON-AWARP described above also serves as deformation analysis software. In this embodiment, TIMON-AWARP is used as deformation analysis software.
The deformation analysis device 106 performs deformation analysis by using the basic data stored in the basic data file 120 and the flow analysis results stored in the flow analysis result data file 122. The deformation analysis device 106 performs deformation analysis at each timing from the start of the filling process to the end of the pressure holding process. Hereinafter, the contents of the deformation analysis executed at the timing ts in FIG. 8 will be described. The deformation analysis is similarly performed at other timings.
FIG. 12 shows the material 50 in the cavity 74 at timing ts. The material 50 maintains a solid line shape in the cavity 74. However, a force D2 (hereinafter referred to as “deformation force”) that tries to deform acts on the material 50 due to various causes. As the reason for the deformation force D2 acting, the shrinkage of the material 50, the difference in the solidification speed in the material 50, the residual stress, etc. are estimated. Since the deformation force D2 acts on the material 50, if the mold 72 is opened at the timing ts, the material 50 is deformed into a broken line shape. The deformation analysis is easy to understand when it is assumed that the shape after deformation when the material 50 is freely deformed is calculated. In the actual deformation analysis, the volume shrinkage rate (degree and direction of shrinkage) of each finite element m when the material 50 is freely deformed at the timing ts is calculated. This is nothing but calculating the deformed shape when the material 50 is freely deformed at the timing ts.
The deformation analysis apparatus 106 also calculates the volume shrinkage rate of each finite element m at other timings. That is, the deformation analysis device 106 calculates a change with time of the volume shrinkage rate of each finite element m.

The deformation analysis result data file 124 illustrated in FIG. 9 stores the deformation analysis result calculated by the deformation analysis device 106. That is, the deformation analysis result data file 124 stores a change with time of the volume shrinkage rate of each finite element m. This is equivalent to storing the deformed shape when the material 50 is freely deformed at each timing.
The deformation analysis result stored in the deformation analysis result data file 124 is used in stiffness analysis described later.

The rigidity data file 126 stores resin stress-strain characteristic data. The user can input stress-strain characteristic data using the input device 102. The computer 100 creates a stiffness data file 126 that stores the input stress-strain characteristic data.
In this embodiment, stress-strain characteristic data when the resin is completely solidified is used. The resin before actually opening the mold is in a semi-solid state, and it is preferable to use the stress-strain characteristic data when the resin is in a semi-solid state. However, the present inventors have confirmed that even if the stress-strain characteristic data in the case where the resin is completely solidified is used, a rigidity analysis result with a certain degree of accuracy can be obtained.
The stiffness data stored in the stiffness data file 126 is used in stiffness analysis described later.

The constraint condition data file 128 stores constraint conditions used in stiffness analysis described later. The user can input constraint condition data using the input device 102. The computer 100 creates a constraint condition data file 128 that stores the input constraint condition data.
The constraint conditions stored in the constraint condition data file will be described with reference to FIG. The constraint condition of the present embodiment is a condition that the end portions 50a and 50b of the material 50 are fixed at the positions. How this constraint condition is used will be described in detail later.

The rigidity analysis apparatus 108 shown in FIG. 9 functions by the operation of the rigidity analysis software. The rigidity analysis software of the present embodiment is Nastran (MS Software Co., Ltd.).
Data used by the stiffness analyzer 108 is listed below.
(1) Cavity shape data (molded product shape data) stored in the basic data file 120.
(2) Deformation analysis results stored in the deformation analysis result data file 124.
(3) Stress-strain characteristic data stored in the stiffness data file 126.
(4) Restriction condition data stored in the restriction condition data file 128.
The stiffness analyzer 108 executes the stiffness analysis of the material 50 using each of the above data. The stiffness analyzer 108 performs stiffness analysis at each timing from the start of the filling process to the end of the pressure holding process.

Hereinafter, the content of the stiffness analysis executed at the timing ts in FIG. 8 will be described. The stiffness analysis is similarly executed at each other timing.
The deformation analysis result data file 124 stores the volume contraction rate of each finite element m when the material 50 is freely deformed at the timing ts. That is, the broken line shaped material 50 of FIG. 12 is stored. In the rigidity analysis, a constraint condition that the end portions 50a and 50b of the material 50 are fixed at the positions is used. Under this constraint condition, the material 50 is contracted based on the volume contraction rate of each finite element m at the timing ts. In this case, a force vector acting on each finite element m is obtained from the stress-strain characteristic data stored in the stiffness data file 126. This is easy to understand when considered as follows.
That is, a force is applied to the broken-line-shaped material 50 so that the end 50a ′ of the broken-line-shaped material 50 is returned to the end 50a and the end 50b ′ of the broken-line-shaped material 50 is returned to the end 50b. (Referred to as "return force"). The magnitude of the return force is obtained from the stress-strain characteristic data stored in the stiffness data file 126. The stiffness analyzer 108 may be considered to calculate a force vector acting on each finite element m when a force opposite to the return force is applied to the solid line-shaped material 50 under the above-described constraint conditions. This force vector is a force vector (deformation-induced force vector) acting on each finite element m due to the solid line-shaped material 50 attempting to deform into a broken line shape.
FIG. 12 shows one back surface side finite element mrx constituting the back surface 54 of the curvature portion 56. The deformation-induced force vector of the back surface side finite element mrx is Brx (ts).
The rigidity analysis apparatus 108 of the present embodiment calculates a deformation-causing force vector of each back side finite element mr. On the other hand, the stiffness analyzer 108 does not calculate a deformation-causing force vector for each surface-side finite element mh. Thereby, the amount of calculation can be reduced.

If the deformation-induced force vector of each back-side finite element mr is known, the force (deformation-induced normal force) that each back-side finite element mr applies to the mold 72 in the vertical direction can be calculated. For example, in the case of the back surface side finite element mrx shown in FIG. 12, the deformation-induced normal force BPrx (ts) can be calculated from the deformation-induced force vector Brx (ts). The stiffness analyzer 108 calculates a deformation-induced normal force for each back side finite element mr.
The stiffness analyzer 108 performs stiffness analysis at other timings, and calculates a deformation-induced normal force of each back side finite element mr. Thereby, the temporal change of the deformation-induced normal force of each back side finite element mr is obtained.

The stiffness analysis result data file 130 illustrated in FIG. 9 stores the stiffness analysis result calculated by the stiffness analysis device 108. That is, the stiffness analysis result data file 130 stores a change with time of the vertical force due to deformation of each back surface side finite element mr.
The stiffness analysis result stored in the stiffness analysis result data file 130 is used by the arithmetic device 110 described below.

The arithmetic unit 110 calculates the injection-induced normal force of each backside finite element mr from the injection-causing force vector of each backside finite element mr stored in the flow analysis result data file 122. FIG. 13 shows one backside finite element mrx. For example, at the timing ts, the injection cause force vector of the back surface side finite element mrx is Arx (ts). The arithmetic unit 110 calculates the injection-induced vertical force (force applied in the vertical direction with respect to the mold 72) APrx (ts) of the back surface side finite element mrx from the injection-induced force vector Arx (ts). The arithmetic unit 110 also calculates the injection-induced normal force from the injection-caused force vector of the other back-side finite element mr for each of the other back-side finite elements mr. Thereby, the injection induced normal force of each back surface side finite element mr at the timing ts is calculated.
The arithmetic unit 110 also calculates the injection-induced normal force of each back surface side finite element mr at other timings. Thereby, the temporal change of the injection-induced normal force of each back surface side finite element mr is calculated.

The arithmetic unit 110 calculates the sum of the injection-induced normal force and the deformation-induced normal force of each back side finite element mr. The injection-induced normal force of each back side finite element mr is obtained by the above calculation. The deformation-induced normal force of each back side finite element mr is stored in the stiffness analysis result data file 130.
For example, at the timing ts, the injection-induced normal force of the back surface side finite element mrx is APrx (ts). Further, at the timing ts, the deformation-induced normal force of the back surface side finite element mrx is BPrx (ts) (see FIG. 13). The arithmetic device 110 calculates the sum of the injection normal force APrx (ts) and the deformation normal force BPrx (ts). The arithmetic unit 110 also calculates the sum of the injection-induced vertical force and the deformation-induced vertical force of the other back surface side finite element mr for each of the other back surface side finite elements mr. Thereby, the sum of the injection-induced normal force and the deformation-induced normal force of each back surface side finite element mr at the timing ts is calculated.
The arithmetic device 110 also calculates the sum of the injection-induced vertical force and the deformation-induced vertical force for each back surface side finite element mrx at other timings. Thereby, the temporal change of the sum of the injection-induced normal force and the deformation-induced normal force of each back side finite element mr is calculated.
Hereinafter, the sum of the injection-induced normal force and the deformation-induced normal force is referred to as “calculation result”.

The output device 112 displays the calculation result obtained by the calculation device 110. The output device 112 can display the calculation result of each back side finite element mr at each timing. For example, the output device 112 can display the calculation result of each back surface side finite element mr at the timing ts. By viewing this, the user can know the air pressure required for air to spread over the entire back surface 54 of the material 50 at the timing ts. For example, when the calculation result (APrx (ts) + BPrx (ts)) of the back surface side finite element mrx is the maximum among the calculation results of the back surface side finite element mr at the timing ts, the air pressure exceeding that value is adopted. Then, it can be seen that the air spreads over the entire back surface 54 of the material 50 at the timing ts. The user can know the minimum required air pressure by looking at the display content of the output device 112. Thereby, it turns out that what is necessary is just to employ | adopt the pump 82 which can implement | achieve this air pressure.
As described above, in the rigidity analysis of the present embodiment, the stress-strain characteristic data when the material 50 is completely solidified is used. However, in reality, the material 50 is in a semi-solid state at the timing ts. Therefore, the deformation-induced normal force BPrx (ts) of the back surface side finite element mrx obtained by the rigidity analysis of this embodiment is larger than the actual deformation-induced normal force. For this reason, even if the same value as the sum of APrx (ts) and BPrx (ts) is adopted as the air pressure, the air should spread over the entire back surface 54 of the material 50 at the timing ts. The user may adopt the same value as the sum of APrx (ts) and BPrx (ts) as the air pressure.

  As described above, the output device 112 can display the calculation result at each timing as well as the calculation result at the timing ts. For this reason, the user can determine the timing at which air is desired to spread over the entire back surface 54 of the material 50 in consideration of the calculation result at each timing.

In the present embodiment, the molded product 50 is injection-molded based on the calculation result obtained by the computer 100. In this injection molding method, air is injected at the timing ts. Further, it is assumed that the calculation result of the back surface side finite element mrx is maximum at the timing ts.
In this injection molding method, a process of filling the cavity 74 with a resin is performed. The resin used here is a resin defined by the material property data stored in the basic data file 120 described above. The filling process is performed according to the injection condition data stored in the basic data file 120. Further, the injection molding apparatus 70 has a mold temperature distribution stored in the basic data file 120.
When the filling process is completed, the pressure holding process is performed. The pressure holding process is performed according to the injection condition data stored in the basic data file 120.
A step of injecting air is performed at timing ts during the pressure holding step. As the air pressure, the same value as the calculation result of the back surface side finite element mrx at the timing ts is adopted. Thereby, air spreads over the whole area of the back surface 54 of the material 50 at the timing ts. After the timing ts, it is guaranteed that the material 50 is solidified with the back surface 54 separated from the mold 72. That is, it is assured that the material 50 is solidified with the surface 52 in contact with the mold 72.
If this injection molding method is implemented, the surface 52 of the molded product 50 can be finished in the intended shape.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
The modifications of the above embodiment are listed below.
(1) When the user determines the timing (for example, ts) at which air is desired to spread over the entire back surface 54 of the material 50, the flow analysis device 104 executes the flow analysis up to the timing ts, and then Subsequent flow analysis need not be performed. In this case, the deformation analysis device 106 performs the deformation analysis only for the timing ts, and does not execute the deformation analysis at other timings. In addition, the stiffness analyzer 108 performs the stiffness analysis only for the timing ts, and does not perform the stiffness analysis at other timings.
(2) Moreover, it is not necessary to calculate the injection-induced normal force and the deformation-induced normal force for all the back surface side finite elements mr. The force that the semi-solidified material 50 tends to deform concentrates on the curvature portions 56 and 58 of the material 50. The back surface side finite element mr constituting the back surface 54 of the curvature portions 56 and 58 has a deformation-induced normal force larger than that of the back surface side finite element mr of other portions. Therefore, it is expected that the sum of the injection-induced normal force and the deformation-induced normal force is also increased in each of the back surface side finite elements mr of the curvature portions 56, 58. For this reason, the injection-induced normal force and the deformation-induced normal force are calculated for each back surface side finite element mr of the curvature portions 56, 58, and the injection-induced normal force and the deformation cause are calculated for each back surface side finite element mr of the other part. It is not necessary to calculate the normal force.
(3) Also, one back side finite element mr (for example mrx) that maximizes the sum of the injection-induced normal force and the deformation-induced normal force is specified in advance from among the back side finite elements mr of the curvature portions 56 and 58. If it is possible to calculate the injection-induced normal force and the deformation-induced normal force for the back surface side finite element mrx, and calculate the injection-induced normal force and the deformation-induced normal force for each other back surface side finite element mr. If the modified examples (1) to (3) are adopted, the amount of calculation of the computer 100 can be reduced.

(4) In the stiffness analysis of the above embodiment, stress-strain characteristic data when the material 50 is completely solidified is used. However, when the stress-strain characteristic data at the timing ts is known, the stiffness analysis at the timing ts may be performed using the data. In this way, accurate rigidity analysis results can be obtained.
Further, for example, it may be assumed that about half of the material 50 is solidified at the timing ts. From the stress-strain characteristic data when the material 50 is completely solidified, the stress-strain characteristic data when about half of the material 50 is solidified may be obtained. The stress analysis at the timing ts may be executed using this stress-strain characteristic data.
In addition, when using the stress-strain characteristic data when the material 50 is completely solidified, the stress-strain characteristic data may be corrected from the experimental results obtained by actually performing the injection molding. Good.

(5) As shown in FIG. 6, the material 50 in the cavity 74 tends to deform in the direction D2. The material 50 in the cavity 74 tries to deform in the D3 direction, but the amount of deformation is very small. For this reason, the deformation in the D3 direction can be ignored.
In the rigidity analysis of the above embodiment, a force vector (deformation-induced force vector) acting on each back side finite element mr due to the material 50 attempting to deform in both the arrow D2 direction and the arrow D3 direction is calculated. is doing. However, the stiffness analyzer 108 may perform the stiffness analysis while ignoring the deformation force in the direction of the arrow D3. In this case, the stiffness analyzer 108 contracts the material 50 in a direction (so-called plane direction) along the two-dot chain line L in FIG. In this case, only the deformation force in the direction of the arrow D2 acts on the material 50, and the deformation force in the direction of the arrow D3 is ignored.

(6) In the above embodiment, the stiffness analysis is performed using the condition for constraining the end portions 50a and 50b of the material 50. However, the constraint conditions can be changed variously. For example, not only the end portions 50a and 50b but also other conditions may be used. Moreover, you may utilize the conditions which restrain only another part, without restraining edge part 50a, 50b.

(7) The output device 112 may display not only the calculation result obtained by the calculation device 110 but also the stiffness analysis result stored in the stiffness analysis result data file. When the computer 100 does not realize the function of the arithmetic device 110, the output device 112 may display only the rigidity analysis result.

  The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

The example of the molded article which has a curvature part into which a back surface becomes an inner side is shown. Fig. 2 briefly shows an apparatus for injection molding the molded article of Fig. 1; A semi-solidified material is shown. The figure by which a part of molded article was divided | segmented into the finite element is shown. The figure for demonstrating a mode that the material of a semi-solidified state tends to deform | transform is shown. An example of the injection molded product (bumper) of an Example is shown. A device for injection molding a bumper is briefly shown. The time chart of each process which an injection molding apparatus implements is shown. Each function realized by the injection molding simulation computer is shown. The figure which divided | segmented the bumper into the finite element is shown. An example of storage contents of a flow analysis result data file is shown. The figure for demonstrating a mode that the material of a semi-solidified state tends to deform | transform is shown. The figure for demonstrating the force which acts on one back surface side finite element is shown.

Explanation of symbols

10: Molded product 12: Front surface 14: Back surface 16: Curvature section 20: Injection molding device 22: Molding mold 24: Cavity 50: Molded product 52: Front surface 54: Back surface 56: Curvature section 58: Curvature section 70: Injection molding apparatus 72 : Mold 74: Cavity 100: Injection molding simulation computer 102: Input device 104: Flow analysis device 106: Deformation analysis device 108: Stiffness analysis device 110: Arithmetic device 112: Output device 120: Basic data file 122: Flow analysis result data File 124: Deformation analysis result data file 126: Stiffness data file 128: Restriction condition data file 130: Stiffness analysis result data file

Claims (8)

When the injection-molded product is injection-molded by filling a mold having a cavity for molding an injection-molded product having a curvature portion with the back surface inside, the material in a semi-solid state is formed in the cavity. A simulation computer for calculating a force applied to the mold by the back surface due to the deformation;
A basic data file that stores basic data for flow analysis;
Using the basic data stored in the basic data file, the flow analysis device that performs the flow analysis of the material in the cavity,
A flow analysis result data file storing the flow analysis results obtained by the flow analysis device;
A deformation analysis device that executes deformation analysis of a semi-solidified material at least at a predetermined timing using the flow analysis result stored in the flow analysis result data file;
A deformation analysis result data file storing the deformation analysis results obtained by the deformation analysis device;
A stiffness data file that stores the stiffness data of the material;
Using the deformation analysis result stored in the deformation analysis result data file, the rigidity data stored in the rigidity data file, and the condition for constraining the semi-solidified material in the cavity, at the predetermined timing A simulation computer for injection molding, comprising: a rigidity analysis device that calculates a force applied to the mold by the back surface due to deformation of the semi-solidified material.   The rigidity analysis apparatus is configured to cause the semi-solid state material to be deformed at the predetermined timing for each of a plurality of back surface side finite elements constituting the back surface of the semi-solid state material. 2. The simulation computer according to claim 1, wherein a force applied by the element in a direction perpendicular to the mold is calculated. A stiffness analysis result data file storing stiffness analysis results obtained by the stiffness analyzer;
An arithmetic unit that calculates using the flow analysis result stored in the flow analysis result data file and the stiffness analysis result stored in the stiffness analysis result data file;
For each of a plurality of back surface side finite elements constituting the back surface of a semi-solidified material, the flow analysis device causes the back surface side finite element to form a mold due to material filling or holding pressure at the predetermined timing. To calculate the force applied in the vertical direction,
For each of the plurality of back surface side finite elements constituting the back surface of the semi-solidified material, the computing device causes the back surface side finite element to be in contact with the mold due to filling or holding pressure of the material at the predetermined timing. Calculating the sum of the force applied in the vertical direction and the force applied by the back-side finite element in the vertical direction to the mold due to the semi-solidified material attempting to deform at the predetermined timing. The simulation computer according to claim 2, wherein: Filling a molten mold material with a mold having a cavity for molding an injection-molded article having a curved portion with the back surface inside;
An injection molding method comprising a step of injecting a pressurized fluid exceeding each value obtained by the arithmetic unit of the simulation computer according to claim 3 into the back side of the semi-solidified material simultaneously with or before the predetermined timing. .   The rigidity analysis apparatus is configured to cause the semi-solidified material to deform at the predetermined timing with respect to at least one back-side finite element constituting the back surface of the curvature portion of the semi-solidified material. The simulation computer according to claim 1, wherein a force applied to the mold by the back surface side finite element is calculated. The deformation analysis device performs deformation analysis of a semi-solidified material for each of a plurality of timings,
2. The simulation computer according to claim 1, wherein the stiffness analyzer calculates a force applied to the mold by the back surface due to the semi-solidified material attempting to deform at each of a plurality of timings. . When the injection-molded product is injection-molded by filling a mold having a cavity for molding an injection-molded product having a curvature portion with the back surface inside, the material in a semi-solid state is formed in the cavity. It is a simulation method for calculating by a computer the force applied to the mold by the back surface due to trying to deform,
Creating a basic data file storing basic data for flow analysis;
Using the basic data stored in the basic data file, the flow analysis process that performs flow analysis of the material in the cavity,
Creating a flow analysis result data file storing the flow analysis results obtained in the flow analysis step;
A deformation analysis step of performing deformation analysis of a semi-solidified material at least at a predetermined timing using the flow analysis result stored in the flow analysis result data file;
Creating a deformation analysis result data file storing the deformation analysis results obtained in the deformation analysis process;
Creating a stiffness data file storing the stiffness data of the material;
Using the deformation analysis result stored in the deformation analysis result data file, the rigidity data stored in the rigidity data file, and the condition for constraining the semi-solidified material in the cavity, at the predetermined timing An injection molding simulation method in which a computer executes a rigidity analysis step of calculating a force applied to the mold by the back surface due to deformation of a semi-solidified material. When the injection-molded product is injection-molded by filling a mold having a cavity for molding an injection-molded product having a curvature portion with the back surface inside, the material in a semi-solid state is formed in the cavity. A computer program for calculating a force applied to the mold by the back surface due to deformation.
Creating a basic data file storing basic data for flow analysis;
Using the basic data stored in the basic data file, the flow analysis process that performs flow analysis of the material in the cavity,
Creating a flow analysis result data file storing the flow analysis results obtained in the flow analysis step;
A deformation analysis step of performing deformation analysis of a semi-solidified material at least at a predetermined timing using the flow analysis result stored in the flow analysis result data file;
Creating a deformation analysis result data file storing the deformation analysis results obtained in the deformation analysis process;
Creating a stiffness data file storing the stiffness data of the material;
Using the deformation analysis result stored in the deformation analysis result data file, the rigidity data stored in the rigidity data file, and the condition for constraining the semi-solidified material in the cavity, at the predetermined timing A computer program for causing a computer to execute a rigidity analysis step of calculating a force applied to the mold by the back surface due to the semi-solidified material being deformed.

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