JP2002200662A - Method and apparatus for predicting weld line - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for exactly grasping a weld line generation phenomenon generated during a packing process for casting a molten material in a molding mold and analyzing the weld line easily and promptly, an apparatus for the method, and a storage medium in which a computer program for materializing the analysis method is stored. SOLUTION: Flow analysis is implemented on the basis of a analysis form model for the flow analysis, the generation origin of a flow vector and a weld line is obtained from the results of the analysis, a virtual particle is generated at the origin, and an analysis for predicting the weld line which is the locus of the particle moved along the flow vector is implemented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for forming a molded product such as an injection molded product, a die-cast product, a thixomolded product, a cast product, etc., at a portion where a plurality of flows of a molten molding material are joined in a molding die. The present invention relates to a method and an apparatus for estimating a position of a weld line generated at a portion where a flow velocity changes significantly due to a weld line to be performed or a thickness difference in a molded product mold.

[0002]

2. Description of the Related Art Conventionally, in weld line prediction, a flow analysis is performed, and from a flow pattern obtained as a result, an association angle (see FIG. 9), which is a merge angle at which a plurality of flows join, is calculated, and the association angle is small. It has been believed that moderately strong weld lines are created. For example, Japanese Unexamined Patent Publication (Kokai) No. 7-1529 discloses a method for predicting the strength of the appearance of a weld line in a resin injection-molded product. The following (1) ~
(4) shows the procedure for the method. (1) The shape of a molded product mold is divided into a number of elements, and the velocity vector of the molten resin in each element is obtained by flow analysis. (2) If the velocity vectors of two adjacent elements are on the same plane and intersect, the interface between the two elements is considered to be a weld line. Select as element. (3) An angle formed by the velocity vectors of a plurality of adjacent weld elements is determined as a merging angle at which a plurality of flows of the molten resin merge in the product mold. (4) Comparing all the merging angles, it is predicted that the larger the merging angle is, the stronger the weld line appears, and the smaller the merging angle is, the weaker the weld line appears.

[0003]

In the case of the above prior art,
When the merging angle (association angle) at which multiple flows merged by the flow analysis reaches a certain angle (for example, 180 degrees), it cannot be displayed as a weld line, and the weld line is treated as if it had disappeared. . Considering the actual weld line generation phenomenon, the molten resin is often of high viscosity and turbulence is unlikely to occur, so even after the branched flows merge, the molten resins transported from different flows are mixed together Very little. Therefore, even if the merging angle is a certain angle (for example, 180
Even in the case where the temperature becomes zero, the weld line often does not disappear until it reaches the part where the flow stops or the end of the shape. For this reason, the conventional technology that considers that the weld line disappears when the merge angle obtained by the flow analysis reaches a certain prescribed angle (for example, 180 degrees) cannot accurately grasp the actual weld line generation phenomenon. .

The present invention has been made in view of the above circumstances, and a method and apparatus for more accurately grasping the actual phenomenon of weld line generation and more easily predicting the position of a weld line, and utilizing these. It is an object of the present invention to provide a method for manufacturing a molded article.

[0005]

According to the present invention, in order to solve the above-mentioned problems, in predicting a weld line position by a flow analysis in a molding process of a molded article, an analytical shape model of the molded article, material physical properties, An analysis condition reading step of reading data and molding condition data into a memory;
A flow analysis step of performing a flow analysis based on the analysis shape model, the material property data and the molding condition data; and obtaining a flow vector at each element or node in the analysis shape model based on an output result of the flow analysis step. A flow vector creation step, a virtual particle generation step of finding a position of a virtual particle serving as a starting point of a weld line, and a virtual particle tracking step of finding a trajectory of the virtual particle moving along the flow vector, Is a weld line, a weld line prediction method is provided.

According to another aspect of the present invention, in predicting a weld line position by flow analysis in a molding process of a molded product, an analysis shape model of the molded product, material property data, and molding condition data are stored in a memory. Analysis condition reading means, and the analysis shape model, a flow analysis means for performing a flow analysis based on the material property data and the molding condition data, each of the analysis shape model based on the output result of the flow analysis means Flow vector creation means for finding a flow vector at an element or a node, virtual particle generation means for finding the position of a virtual particle serving as a starting point of a weld line, and virtual particle tracking for finding a trajectory of the virtual particle moving along the flow vector Means, and the trajectory is a weld line. Predicting apparatus is provided.

According to another aspect of the present invention, there is provided a computer program for executing each step of the above weld line prediction method using a computer.

According to another aspect of the present invention, there is provided a computer-readable storage medium storing the above-described computer program.

According to another aspect of the present invention, the position of a weld line is predicted using the above-described method for predicting a weld line, and the shape, material properties and molding conditions of a molded product are finally determined. A method for producing a molded article is provided.

Hereinafter, the terms will be defined.

In the present invention, the "analysis shape model" refers to nodes, elements, and the like used for flow analysis using a computer.
Refers to data described by element characteristics and the like. The “flow vector” refers to a vector representing the direction of the flow of the molten material at each element or each node. The flow vector may further include the velocity of the flow, and may be held as a set of velocity components in each direction. "Molding conditions" refer to the molten material temperature, filling time, filling speed, filling pressure, mold temperature, and the like.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a method and apparatus for predicting a weld line according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a block diagram showing one embodiment of an apparatus for performing weld line prediction according to the present invention. In this embodiment, (100) is a computer, (101) is a keyboard, (102) is a mouse, (103) is a display, and (104) is an auxiliary storage device. (104)
In addition to hard disk, FD, MO (Magneto-optical disk),
Removable auxiliary storage devices such as PDs, DVDs (digital versatile discs), etc. are also available.

The auxiliary storage device (104) includes a CAD data storage means (105) and an analysis shape model storage means (10
6), a flow analysis result storage means (107), and a virtual particle tracking trajectory storage means (108).

The computer (100) includes a CPU and a CAD data creating means (109) and an analysis shape model creating means (11) comprising a subroutine developed on a memory.
0), analysis condition reading means (111), flow analysis means (112), flow analysis result reading (113), flow vector creation means (114), virtual particle generation means (11)
5), a virtual particle tracking means (116) is included.

The CAD data creation means (109) is a means for creating a molded product shape on a computer,
(SDRC), CATIA (Dassult), UniGraphics (U
This is an existing technology installed in many CAD systems such as GS.

The analysis shape model creation means (110)
For the CAD data created by the D data creation means (109), a neutral plane is created from the CAD data as shown in FIG. 3 to automatically create a two-dimensional shell element or automatically create a three-dimensional solid element. create. As described above, methods for creating an analysis shape model from CAD data include I-DEAS (made by SDRC),
CATIA (Dassult), UniGraphics (UGS) and other existing CAD technologies.

The flow analysis means (112) performs a flow analysis based on the analysis shape model created by the analysis shape model creation means (110) and the material properties and analysis conditions read into the memory by the analysis condition reading means (111). To obtain the pressure, temperature, flow velocity, etc., of TIMON (Toray), MOLDFLOW
(MOLDFLOW) is an existing technology installed in flow analysis software. The shape, material properties, and molding conditions may be read into the memory from the auxiliary storage device (104). However, when the data already developed on the memory is used as it is, the reading is performed with the above development. Is considered to have been done.

The flow vector creation means (114) creates a velocity vector of each element or each node in an arbitrary analysis step, which is one of the results of the flow analysis performed by the flow analysis means (112). Is a flow vector. Also, a flow front arrival time gradient vector may be created based on the flow front arrival time data, which is one of the results of the flow analysis performed by the flow analysis means (112), and this may be used as the flow vector.

The virtual particle generation means (115) generates a starting point at which a weld line is formed. For example, the flow tip arrival time, which is one of the output results of the flow analysis performed by the flow analysis means (112), Based on the data, the flow fronts are grouped, and the position where the flow fronts of different groups meet is defined as the starting point of the weld line. Alternatively, the flow fronts may be grouped at the time of the flow analysis performed by the flow analysis means (112), and the position where the flow fronts of different groups merge may be set as the weld line start position. In addition, a position that is equal to or smaller than an arbitrary angle of association when the flow analysis performed by the flow analysis unit (112) is performed may be set as the weld line starting point. In addition, the flow analysis means (11
From the results of the association angle distribution output from the flow analysis performed in 2), a position at or below an arbitrary association angle is defined as a weld line starting point. The arbitrary association angle is set by the user according to the type of resin and the size of the element. Then, virtual particles are generated at the weld line start position.

The virtual particle tracking means (116) moves the virtual particle along the flow vector created by the flow vector creation means (114) and stores the coordinates of the position where the virtual particle has arrived at each time. . Alternatively, the position of the node closest to the coordinates of the position where the virtual particle has reached at each time is stored.

A line connecting the coordinates or nodes of the positions where the virtual particles have reached at the stored times is a weld line.

FIG. 4 shows a specific example of weld line prediction.

FIG. 4 shows a hole having a diameter of 15 mm at the center.
Drawing and CAD data of a flat plate having a taper of 150 mm x 50 mm and a thickness of 2 mm to 5 mm. FIG. 5 shows an analysis shape model automatically created by two-dimensional shell elements, which is composed of 622 nodes and 1116 elements.

For the shape shown in FIG. 5, nylon 6 manufactured by Toray Industries, Inc.
FIG. 6 shows a flow pattern in which a flow analysis was performed using the resin physical property data of FIG.

FIG. 7 is a weld line obtained by analyzing the flow association angle according to the prior art.

FIG. 8 shows a weld line output according to this embodiment. In this manner, the position of the weld line, which cannot be completely extracted by the conventional angle of association, can be grasped.

By estimating the position of the weld line in this way, the position of the weld line can be known under any manufacturing conditions. If necessary, the shape of the molded product, material properties and molding conditions can be changed. The final manufacturing conditions may be determined by moving the weld line to a desired position by making appropriate corrections, and the molded product may be actually manufactured based on the results.

As described above, the weld line prediction device of the present embodiment is realized by a computer and software (program) loaded on the computer. Such software is available on floppy disks, CD-R
It is distributed through a tangible storage medium such as an OM or a transmission means such as a wireless or wired network.

[0030]

According to the present invention, it is possible to easily and accurately predict the position of the weld line based on the result of the flow analysis. As a result, the position of the weld line due to a change in the product thickness or the gate position can be examined from the product / die design stage, and the product / die design can be made more efficient.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a flowchart of an embodiment of the present invention.

FIG. 3 is a diagram showing a CAD shape and an analysis shape model.

FIG. 4 is a plan view of a 150 × 50 × (2 to 5) taper wall thickness and CAD data of the plan view.

FIG. 5 is an analysis shape model for the flat plate of FIG. 5;

FIG. 6 is a flow pattern for the analysis shape model of FIG. 6;

FIG. 7 is a conventional weld line display for the flow pattern of FIG. 7;

FIG. 8 is a weld line display according to the present invention for the flow pattern of FIG. 7;

FIG. 9 is an explanatory diagram of an association angle.

[Explanation of symbols]

 100 Computer 101 Keyboard 102 Mouse 103 Display 104 Auxiliary storage device 105 CAD data storage means 106 Analysis shape model storage means 107 Flow analysis result storage means 108 Weld line origin movement locus storage means 109 CAD data creation means 110 Analysis shape model creation means 111 Flow Analysis means 112 Flow analysis result reading means 113 Flow vector creation means 114 Virtual particle generation means 115 Virtual particle tracking means

Claims (5)

[Claims] 1. A method for predicting a weld line position by flow analysis in a molding process of a molded article, an analysis condition reading step of reading an analytical shape model, material property data and molding condition data of the molded article into a memory; A shape model, a flow analysis step of performing a flow analysis based on the material property data and the molding condition data, and a flow vector for obtaining a flow vector at each element or node in the analysis shape model based on an output result of the flow analysis step A virtual particle generation step of obtaining a position of a virtual particle serving as a starting point of a weld line; and a virtual particle tracking step of obtaining a trajectory of the virtual particle moving along the flow vector, wherein the trajectory is welded. A method for predicting a weld line, wherein the method is a line. 2. An analysis condition reading means for reading an analysis shape model, material physical property data and molding condition data of a molded article into a memory when predicting a weld line position by a flow analysis in a molding process of the molded article; A flow model for performing flow analysis based on the shape model, the material property data and the molding condition data, and a flow vector for obtaining a flow vector at each element or node in the analysis shape model based on an output result of the flow analysis means Creating means, virtual particle generating means for determining a position of a virtual particle serving as a starting point of a weld line, and virtual particle tracking means for determining a trajectory of the virtual particle moving along the flow vector, wherein the trajectory is welded. A weld line predicting device characterized by a line. 3. A computer program for executing each step of the weld line prediction method according to claim 1 using a computer. 4. A computer-readable storage medium storing the computer program according to claim 3. 5. A molding for predicting a weld line position using the weld line prediction method according to claim 1, finalizing the shape, material properties and molding conditions of the molded product, and manufacturing the molded product based on the result. Product manufacturing method.