JPH09314307A - Injection molding product manufacturing plan - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily execute an evaluating decision of a filling behavior and to reduce the producing cost of an injection formed product by investigating a defect predicting parameter at the time between the start of filling of molten metal and the completion of filling thereof. SOLUTION: A shape model divided into minute elements 1, 2 is prepared and material data and injecting condition data are prepared. A required time is divided into arbitrary number of times. A numerical analysis of fluid condition of molten materials 3, 4 is performed by using the numerical analysis method based on analyzing data and analyzing condition. A parameter introduced by the expression (1) related to the parts 3, 4 which the molten material is filled up in a metallic mold is calculated, and the numerical distribution and the variation with time of the parameter is graphically outputted. (|V1 | |V2 | sinθ/2) (exp(TL-T)/t)...(1) Wherein, θ is angle formed with velocity vectors of adjacent two elements and TL is the starting temp. of solidification of the molten metal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention determines the optimum method for producing a high-quality product without defects and the optimum injection condition of a molten material by numerical analysis in the injection molding of a molten material such as a cast product or resin. The present invention relates to an evaluation method for directly judging the quality of the filling behavior when the molten material flows into the mold from the numerical analysis result.

[0002]

2. Description of the Related Art Conventionally, in a flow analysis of filling behavior in a mold in injection molding with a molten material, a micro element for performing a flow analysis from a molded product molded by injection molding and a mold used for injection molding. Create a shape model divided into two, and use numerical analysis methods such as the difference method, the finite element method, the boundary element method, and the FAN method to express the continuity equation that the incompressible fluid must satisfy and the equation of motion of the fluid. It is common to perform calculations using the Navier-Stokes equation and the energy equation for evaluating the thermal energy of a fluid as a basic equation.

An example of analysis in which a flow analysis and a heat conduction analysis are combined as an analysis of filling behavior of a molten material in a mold (Otsuka et al .:
Casting Volume 60, No. 12 (1988), 757: "Computer flow analysis system for die casting castings") has been reported.

As a method for evaluating the analysis result in the injection molding simulation of the molten material in such a mold, the filling condition of the molten material is displayed by filled isochronous lines, or the pressure distribution and the vorticity distribution. , The flow velocity distribution, temperature distribution, etc. are displayed, and the quality of the filling behavior is evaluated from these analysis results.

[0005]

When a molded product is manufactured by injection molding of a molten material such as a casting or a resin, the filling behavior of the molten material has a great influence on the quality of the product. If the filling behavior during manufacturing is improper, fatal defects occur for the product such as entrapment of air bubbles in the product (blowhole), molten metal (weld line), and defective filling. In order to prevent the occurrence of these defects, it is necessary to optimize the manufacturing method such as the injection speed and temperature of the molten material, the mounting position and number of gates and runners, the mold temperature and the cooling method. A trial-and-error optimization method that relies on past experience and intuition is adopted.

In addition, CAE (Computer Aided Engineeri)
ng) technology has also been tried to utilize computer simulation to optimize the manufacturing plan. At present, the physical properties of the molten material, the shape of the molded product, the temperature of the molten material, the mold temperature, the filling speed, etc., which are used as the data required for the analysis, are input to perform a flow analysis in the injection molding of the molten material, and the filling status The suitability of manufacturing conditions is evaluated from the analysis results of pressure distribution, vorticity distribution, flow velocity distribution, temperature distribution, etc.

However, in the above-described conventional method of displaying various analysis results in the injection molding simulation, individual information such as the filling state of the molten material, the pressure distribution, the vorticity distribution, the flow velocity distribution, and the temperature distribution must be faithfully represented. Can, but
From this information, it is not possible to directly determine whether the filling situation is suitable for producing a sound product without defects. To evaluate the flow analysis result in injection molding of molten material, whether filling is proceeding in order based on information such as the filling status of molten material, pressure distribution, vorticity distribution, flow velocity distribution, temperature distribution, or final filling The human being comprehensively judges the analysis results obtained on whether the part is in the proper position, whether there is a part where the flow is turbulent, etc. to determine where the defect occurs in the product as a molded product. Predict or guess.

However, in such a flow analysis result evaluation method, there is a large part that depends on the past experience and intuition of the person who makes the judgment, and therefore the evaluation of the analysis result may differ depending on the person making the judgment. Therefore, it is very difficult to accurately grasp and evaluate the phenomena such as the turbulence of the flow generated during the filling and the generation of bubbles due to the entrainment of air by such a method of evaluating the flow analysis result.

Therefore, an object of the present invention is to provide a method for evaluating the flow analysis result in the injection molding of a molten material, which can easily determine the suitability of the filling condition from the flow analysis result in the injection molding of the molten material. .

[0010]

In order to solve the above-mentioned problems, the present invention has been completed by developing a parameter for evaluating a filling condition when a molten metal flows into a mold.

The manufacturing method of an injection-molded article by injection-molding a molten material according to the present invention is achieved by the following steps.

(A) Suitable for numerical analysis methods such as a difference method, a finite element method, a boundary element method and a FAN method for performing numerical analysis from a molded product molded by injection molding and a mold used for injection molding. Create a shape model divided into minute elements, create physical property data showing physical properties such as temperature of mold and molten material, thermal conductivity, specific heat, and further speed, temperature, time when injecting molten material Create injection condition data such as.

(B) In the numerical analysis, the time required from the start of the filling of the molten material into the mold to the end of the filling is divided into an arbitrary number.

(C) Based on the analysis data and analysis conditions set in (a) above, the difference method, the finite element method, the boundary element method,
Numerical analysis of the flow state of the molten material is performed using a numerical analysis method such as the FAN method.

(D) The parameters introduced by the equation (1) for the portion filled with the molten material in the mold are calculated from the velocity field and the temperature distribution.

[0016]

[Equation 1]

Equation (1) is based on the flow velocity distribution and the filling condition of the molten material in the mold at each divided time, and the velocity V of two adjacent elements when the molten materials collide with each other.
₁ , V ₂ and the angle θ formed by the velocity vector, the average temperature T of two adjacent elements at the time when the molten material is divided, and the solidification start temperature T _L of the molten material.

(E) The above operation (d) is repeated until the molten material fills the entire cavity.

(F) Graphically output the distribution and temporal change of the parameter size to a display output device such as a CRT or a printer.

By performing the steps (a) to (f) above, the quality of the filling behavior in the injection molding of the molten material is evaluated and judged.

Here, the method of calculating the parameters will be described in detail with reference to the drawings. FIG. 1 is a conceptual diagram for calculating the parameters of the present invention. In reality, the shape is three-dimensional, but for simplification of description, the description will be made with a two-dimensional diagram. Element 1 shown in 1 and element 2 shown in 2 have an analysis area of 4
The elements are divided by polygonal minute elements, and the shaded portions 3 and 4 indicate the portions filled with the molten material in the elements 1 and 2, respectively. 5, the velocity vector of the molten material in the element 1 when the molten materials collide with each other is V
Assuming that the velocity vector of the molten material in the element 2 is V2 as 1,6, the magnitude of each vector is calculated by adding the square of the x, y, z direction components of the vector and taking the route (2) , (3) can be obtained.

[0022]

[Equation 2]

[0023]

(Equation 3)

The collision angle when the molten materials collide with each other can be calculated by the following equation (4) by using the inner product of the vectors.

[0025]

(Equation 4)

The temperature is the temperature T ₁ of element ₁ and the temperature T of element 2.
It is calculated by taking the average of ₂ .

The value of the parameter is calculated using the angle θ and the average temperature obtained for all the adjacent elements,
A parameter for predicting the occurrence of defects is obtained by taking the sum.

The manufacturing method in the injection molding of the molten material according to the present invention is achieved by the following steps.

(G) Shape data required for numerical analysis to simulate a manufacturing method for numerically analyzing the flow behavior of the molten material according to claim 1, mechanical and thermal physical property values of the mold and the molten material, and The inflow velocity is used as input data for numerical analysis.

(H) Numerical analysis of the flow state of the molten material into the cavity using numerical analysis methods such as the difference method, the finite element method, the boundary element method, and the FAN method based on the input data for numerical analysis. .

(I) The quality of the filling behavior is evaluated and judged by using the method for evaluating the flow analysis result in the injection molding of the molten material according to the first and second aspects.

(J) The input data of (g) is changed until it is determined that the judgment result is good.

As described above, the steps (g) to (j) are repeatedly carried out until the analysis result shows that no defect is generated, so that an appropriate manufacturing plan and manufacturing conditions are derived.

According to the manufacturing method of the injection molding product of the molten material according to the present invention, in order to evaluate the quality of the filling condition of the molten material into the mold, the parameters described in claim 1 are filled with the molten material. By checking from the start to the end of filling, the evaluation of the filling behavior can be easily performed.

Generally, in the injection molding of a molten material, the filling behavior in which there is no turbulent flow and the product is filled in order is less likely to cause defects due to the flow. From the result of observing many products in which many defects were actually generated, it was inferred that the defects caused by the molten metal flow were caused by the collision of the molten materials whose temperature decreased to around the solidification start temperature.

Therefore, in order to investigate the quality of the filling behavior of the molten material into the mold, a parameter having a function of the velocity field and the temperature of the molten material during the filling is proposed, and the value or the variation width of the value is used. The quality of the filling behavior in the mold can be determined.

Further, in evaluating the filling state of the molten material in the mold in the injection molding of the molten material, in order to evaluate which part of the molded product is likely to have a defect, an analysis is performed. The shape model consisting of minute elements created for this purpose was divided into arbitrary regions, and the time required from the start of filling the molten material into the mold in the numerical analysis until the end of filling was divided into any number, and each divided The defect occurrence prediction parameters are calculated from the velocity field and the temperature of the molten material during filling in the area of the shape model, and these values are filled from the start of filling the molten material with the values calculated for each part of the divided shape model. By comparing the fluctuation states up to the end, it is possible to determine the site where there is a high possibility that a defect during filling will occur.

Further, before the actual product is manufactured, the filling condition of the molten material for the manufacturing plan given by the numerical analysis is analyzed, and the filling condition is evaluated by using the above-mentioned evaluation method of the filling condition of the molten material, and the filling condition is evaluated. By changing and analyzing the input data until the situation becomes appropriate, it is possible to derive an appropriate manufacturing plan and manufacturing conditions for the product. By going through such means, the trial
It is possible to manufacture high-quality injection-molded products that do not contain defects without optimizing the And-Error strategy. In addition, since it is possible to identify in advance the parts to be modified in the mold for the new plan product by simulation, it is possible to reduce the time and cost required for modifying the mold, and to perform injection molding. The manufacturing cost of the product can be significantly reduced.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 shows an electrical configuration of an apparatus for executing a method for evaluating a flow analysis result in injection molding of a molten material according to the present invention. In the same figure, the filling analysis unit 7 for analyzing the behavior of the molten material such as speed, pressure, temperature, etc. in the process of filling the mold with the molten material, the shape data and physical properties of the object to be analyzed are analyzed. Input data such as data and boundary conditions are given. The filling analysis unit 7 numerically analyzes the process in which the molten material is filled in the mold based on the given input data by using the numerical analysis methods including the difference method, the finite element method, the boundary element method, and the FAN method. To do. The data of the filling state of the molten material in the mold obtained by the numerical analysis is sent to the defect parameter calculation unit 8 at a designated time interval. The defect parameter calculation unit 8 calculates defect prediction parameters from the velocity vector in the region filled with the molten material and the temperature of the molten material, and stores those values on a memory or a storage device such as a magnetic disk. Then, it returns to the filling analysis unit 5 again and repeats until the molten material is filled in the mold. After the completion of the filling analysis, the analysis result stored in the storage device is graphically output to the display output device 9 such as a CRT or a printer. Whether the filling behavior is good or bad is determined from the result output to the display output device 9.

Next, the method of evaluating the flow analysis result in the injection molding of the molten material according to the present invention will be described using an actual application example. The procedure of performing a flow analysis in a mold for a molded product molded by injection molding and a mold used for injection molding is the same as the conventional analysis method. First, in order to perform a flow analysis in a mold, a shape model divided into minute elements for performing a flow analysis is created from a molded product molded by injection molding and a mold used for injection molding. The model used for the analysis is a ring-shaped die cast component as shown in FIG. Since the position of the overflow was not appropriate in the initial plan, the product had uneven gloss that was thought to be entrained by bubbles after the surface was machined. Here, 10 is a gate for injecting a molten material into a mold, 11 is a cavity for forming a product, and 12 is an overflow which is cut off after the product is completed. In this embodiment, an FDM mesh that divides the analyzed portion into orthogonal mesh elements is used. However, depending on the flow analysis program used, triangular elements, quadrangular elements, other polygonal elements, or BFC elements whose boundaries are deformed, etc. Element division is performed on elements that include. The runner position and speed at which the molten material flows and the position and speed at which the molten material flows into the cavity are set as necessary for the shape models of these molded products and molds. By these operations, the setting of the shape data for performing the flow analysis in the injection molding of the molten material is completed.

Further, the setting operation of the physical property data for performing the flow analysis in the injection molding of the molten material is performed. That is, the thermal properties such as the density, specific heat, and thermal conductivity of the mold used, and the thermal properties such as the density, specific heat, and thermal conductivity of the molten material used, and the viscosity coefficient indicating the viscosity, By setting the thermal boundary conditions such as the heat transfer coefficient between the mold and the molten material, the setting work of the physical property data for performing the flow analysis in the injection molding of the molten material is completed. The operation up to this point is the same as the conventional data creation procedure for performing flow analysis in injection molding of molten material.

Therefore, in the present embodiment, the above-described defect prediction parameters are incorporated into a temperature field / flow field coupled analysis program, and the defect positions generated in the actual die-cast product are compared to determine the defect prediction parameters of the present invention. Confirmed its usefulness. When performing the flow analysis here, the defect prediction parameter for each element is calculated from the velocity vector and the temperature distribution in the region filled with the molten material at each time step divided into minute times, and this is stored in the recording medium. This operation is repeated from the start of the filling of the molten material in the mold to the end of the filling in the numerical analysis. Arrange the data saved in the recording medium and set the parameter values of each element to 3
An analysis result as shown in FIG. 4 is obtained by outputting the dimensional graphic.

The magnitude of the defect prediction parameter in each element obtained from the analysis result of FIG. 4 is shown. The display of the results is shown in different colors according to the size of the parameter, and the white part has the largest value. In general, it is considered that the smaller the value of the parameter, the more desirable. This is because the proposed parameter is a value obtained by multiplying the velocity vector of the molten material by a factor that represents the degree of collision and a factor that represents the progress of the solidification phenomenon due to the temperature decrease. It shows that there is no coagulation due to the reduction. Therefore, the entire product used for the analysis of the value of the defect prediction parameter is examined, and a portion having a relatively large value is a portion where a defect is likely to occur. In this example, it can be confirmed that the position 13 where the occurrence of a defect obtained from the analysis result is predicted and the position where the uneven glossiness, which is thought to be the entrainment of bubbles after machining in an actual product, are well matched. It was

Since the value of the defect prediction parameter of the present invention largely varies depending on the shape of the molded product, the inflow rate of the molten material, the planner of the runner or gate, the physical property value of the molten material to be used, the temperature condition, etc., the values of these values are large. It is not possible to make an absolute evaluation based on this. However, it is possible to obtain an appropriate injection molding condition by grasping what kind of change tendency occurs when the manufacturing condition is changed and obtaining the injection molding condition in which the defect prediction parameter becomes the minimum in the entire product. .

[0045]

As is apparent from the above-described embodiments, according to the present invention, a molten material flows into a molded product molded by injection molding and a shape model in which a mold used for injection molding is divided into minute elements. In order to evaluate the quality of the molten material filling in the mold during the flow analysis, the defect prediction parameters that are functions of the molten material velocity vector and temperature during filling are filled from the start of filling the molten material. By checking until the end, the filling behavior can be evaluated and judged easily.

Therefore, according to the present invention, when performing flow analysis of a molded product molded by injection molding, suitability of manufacturing conditions can be easily judged, and a high quality molded product without defects can be obtained from this judgment result. Therefore, the manufacturing conditions such as gate position and number, runner plan, and injection speed can be set appropriately, and the effect of optimizing the manufacturing conditions in injection molding is great. In addition, since it is possible to identify the parts to be modified in the mold beforehand by simulation, it is possible to reduce the time and cost required for modifying the mold, and significantly reduce the manufacturing cost of injection molded products. can do.

[Brief description of drawings]

FIG. 1 is a conceptual diagram for calculating a parameter of the present invention.

FIG. 2 shows an electrical configuration of an apparatus for executing a method for evaluating a flow analysis result in injection molding of a molten material according to the present invention.

FIG. 3 is a shape model divided into minute elements for performing a flow analysis of a molded product molded by injection molding.

FIG. 4 shows a portion where a defect is predicted to occur in the method for evaluating a flow analysis result in injection molding of a molten material according to the present invention.

[Explanation of symbols]

1 ... Microelement 1, 2 ... Microelement 2, 3 ... Portion filled with molten material in element 1, 4 ... Portion filled with molten material in element 2, 5 ... Molten material in element 1 Velocity vector, 6 ... Velocity vector of the molten material in element 2, 7 ...
Filling analysis unit, 8 ... Defect parameter calculation unit, 9 ... Analysis result display unit, 10 ... Gate, 11 ... Product, 12 ... Overflow, 13 ...

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yu Onda 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. (72) Inventor Masa Yamabe 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd.

Claims (3)

[Claims] 1. A method of manufacturing an injection-molded article, wherein a molten material is injection-molded in a mold, wherein the mold is divided into minute elements,
A step of dividing the required time from the start of filling the molten material into the mold to the end of the filling into a desired number of times, based on the flow velocity distribution of the molten material and the filling condition in the mold at each divided time The velocity of two adjacent elements when they collide with each other, the angle formed by the velocity vectors, the average temperature of the two adjacent elements at the time when the molten material is divided, and the solidification start temperature of the molten material A manufacturing method of an injection-molded article, comprising: a step of determining the size of collision, and a step of determining the quality of filling behavior in injection molding of a molten material from the size of the collision. 2. The injection-molded article according to claim 1, wherein the time when the filling behavior of the molten material into the cavity in the mold is deteriorated and the portion inside the cavity where the filling behavior is deteriorated are graphically output. Manufacturing plan. 3. The filling behavior of the molten material in the injection molding of the molten material by performing the flow analysis in the injection molding of the molten material by inputting the shape in the mold and the mechanical and thermal physical property values of the molten material. 3. The manufacturing method for an injection-molded article according to claim 1, wherein the quality of the item is evaluated and judged, the input data is changed until the judgment result is judged to be good, and the above steps are repeated.