JP2001062872A - Method for designing mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suitably design a mold without actually trially molding by sequentially altering a gradient of a mold surface and a mold surface state based on a mold release resisting force to be received at mold surfaces, and obtaining a suitable steel material and the mold surface state in a mold releasing direction. SOLUTION: A mold release resistance value generated at a surface unit of a molding is obtained (S3). If the values falls within predetermined decision values, a gradient and a mold surface state of initial values are adopted as design values (S4). If the initial values exceed the decision values, the gradient is changed (S6). Then, the gradient is again calculated and the mold release resistance value at the changed gradient value is obtained (S8). If the resistance value falls within the predetermined decision value, the changed gradient and the surface state of the initial value are adopted as design values. Similarly, whether the resistance values of the respective surfaces fall within the predetermined decision values or not is decided, and if the resistance values of the surfaces of all the moldings fall within the decision values, the again calculated gradient and the mold surface state of the initial value are adopted as design values (S9).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold design method for optimizing a mold surface which affects mold release in designing a mold for an injection molded product.

[0002]

2. Description of the Related Art When designing an injection mold, a gradient is provided with respect to the mold releasing direction in consideration of the mold releasability. Normally, it is preferable in terms of man-hours to set a uniform slope surface and a standard surface state in terms of design for all mold surfaces in contact with the mold release direction.
However, there are naturally places where demolding is considered difficult,
It determines the gradient with respect to the mold release direction and the surface condition of the gradient surface by trial and error while relying on intuition and experience while looking at drawings and the like.

[0003]

As a result, the releasability is worse than expected when molding is actually performed, and there are cases in which the molded product suffers from mold release failure. Therefore, the process of checking the mold release state by changing the gradient or the surface state is repeated, and it takes a long time until finally a non-defective product is obtained.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and calculates the release force of a surface where a molded product and a mold come into contact with each other when designing an injection molding die. An object of the present invention is to provide a mold design method capable of performing an appropriate mold design without performing an actual molding trial by obtaining a value at which a gradient with respect to a mold release direction and a mold surface state are appropriate.

[0005]

In order to achieve the above-mentioned object, a method of designing a mold according to the first aspect of the present invention is to sequentially analyze filling, holding pressure, and cooling in an injection molding simulation, and to perform analysis after opening the mold. Determine the amount of deformation and the direction of deformation on each surface of the molded product at the start of mold release, and determine the amount of deformation and the direction of deformation on each surface of this molded product. From the stress distribution, the reaction force generated at the contact surface between the mold and the molded product is determined,
From this reaction force, the gradient of the mold surface with respect to the mold release direction, and the mold surface condition, determine the mold release resistance received by each surface, and determine whether this mold release resistance falls within a certain range. Is displayed, and the gradient of the mold surface with respect to the mold release direction and the mold surface state are sequentially changed to obtain an appropriate gradient of the mold surface with respect to the mold release direction and an appropriate mold surface state. It is characterized by.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(First Embodiment) FIG. 1 is a part of a flowchart showing a procedure for carrying out a mold designing method according to the present invention, and FIG. 2 is a remaining part of the flowchart shown in FIG. FIG. 3 is an example of a three-dimensional model of a molded product to which the present invention is applied, and FIG. 4 is a perspective view of a molding die.

[0008] In the three-dimensional shape model data of the molded product shown in FIG. 3 and the mold designed based on the data, the surface where the molded product and the mold shape contact each other is parallel to or close to the release direction. The contact surface of a certain mold (contact surface 1 in FIG. 4)
8), and the surface area of each of the molds with respect to the contact surface is obtained (step S1 in FIG. 1). Next, the filling, holding pressure, and cooling in the injection molding simulation are sequentially analyzed to obtain the deformation amount and the deformation direction generated for each unit element on each surface of the molded product at the time of starting the mold release after the mold opening (FIG. 5).
FIG. 5 is a diagram showing a vector representing a deformation amount and a deformation destination generated for each unit element of a molded product.

The data of the direction and amount of deformation of the molded article are obtained by a simulation based on the analysis such as the injection molding simulation. Can be obtained from the data determined by measurement (FIG. 6). FIG. 6 is a diagram illustrating deformation vector data of a deformation amount and a deformation direction of a molded product.

The mold release direction, which is the direction in which the molded product comes out of the mold, is determined at the time of designing the bridge portion of the mold, and is obtained from the result. The standard values of the gradient of the mold surface and the mold surface state with respect to the mold release direction are obtained by key input as initial values or from a database (step S).
2).

Based on the amount of deformation and the direction of deformation of each unit element of the molded product at the start of the mold release obtained in step S2, the unit of each surface of the molded product from the mold surface where the unit element of each surface of the molded product comes into contact The stress distribution received by the element is determined, the reaction force received from the mold surface received by the unit element on each surface of the molded product is determined from the stress distribution received by the unit element on each surface of the molded product, and the mold release determined in step S2 The slope of the mold surface with respect to the direction and the initial value of the mold surface state, and the mold release resistance received by the unit element on each surface of the molded product from the mold release direction are determined. By adding the release resistance values received for each surface of the molded product, the release resistance value generated for each surface of the molded product is obtained (step S3).

If the release resistance value generated for each surface unit of the molded product obtained in step S3 is within the predetermined release resistance determination value, it is determined that there is no problem in the release property and step S
The values of the gradient of the mold surface and the mold surface state with respect to the mold release direction obtained in Step 2 become the design values as they are. In the same manner, it is determined whether or not the release resistance value generated for each surface unit of the molded product for each applicable surface of the molded product is within a predetermined release resistance determination value. If the surface is within the release resistance determination value, it is determined that there is no problem in the release property, and Step S
The gradient of the mold surface with respect to the mold release direction and the value of the mold surface state obtained in step 2 become design values as they are, and the process ends (step S4).

In step S4, when a release resistance value generated for each surface unit of the molded product obtained in step S3 exceeds a predetermined release resistance determination value, a surface of the corresponding molded product is determined. Is displayed on the three-dimensional shape model data (step S5) (FIG. 6). FIG. 7 is a diagram illustrating an example in which a surface having poor releasability is displayed in the three-dimensional shape model data.

In step S5, the gradient of the mold surface with respect to the mold release direction is changed with respect to the surface of the molded product displayed on the three-dimensional model data as a surface exceeding the mold release resistance determination value. The gradient of the mold surface with respect to the mold release direction used for the change may be obtained from a data file such as a database of predetermined standard gradient values, or may be given by a person (step S6). When changing the gradient value of the mold surface with respect to the mold release direction in step S6,
By changing the gradient value of the mold surface, it is checked whether or not the shape on the molded product side corresponding to the mold surface to be changed is established. As an example, consider the case of FIG. FIG. 8 is a diagram illustrating an example in which the tip shape portion of the molded product causes a functional defect by changing the slope surface in the mold release direction.

The shape portion 1 includes a surface (surface 1 in FIG. 8) exceeding the release resistance determination value. One way to reduce the release resistance of this surface is to increase the slope of the mold surface in the release direction. When the thickness of the root portion (FIG. 8A) of the protrusion of the shape portion 1 is fixed and the gradient value of the mold surface with respect to the mold release direction is changed to a relatively large value, the shape of the tip portion of the shape portion 1 (FIG. 8B) The thickness of the molded product becomes too thin, which causes a problem in the product function of the molded product. Therefore, it is determined whether or not the gradient value of the mold surface with respect to the changed release direction is a value that causes a problem such as, for example, an excessively small thickness in the product function (step S7).

The mold surface gradient value with respect to the mold release direction which is obtained in step S7 and has no problem in product function,
The mold surface state obtained in 2 is the initial value, the mold release direction determined at the time of mold design, and the unit element of each surface of the molded product at the start of mold release after the mold opening obtained in step S2. Is calculated again from the amount of deformation and the direction of deformation occurring in step (1), and the release resistance at the changed gradient value is obtained (step S8).

In step S5, the surface of the molded product displayed on the three-dimensional shape model data as the surface exceeding the release resistance determination value is a mold release generated for each surface unit of the molded product calculated again in step S8. If the resistance value is within the predetermined release resistance determination value, there is no problem in the release property, and the gradient of the mold surface with respect to the release direction determined in step S7 and the mold determined in step S2. The value of the surface state becomes the design value as it is. Similarly, if there is a molded product surface displayed on the three-dimensional shape model data as a surface exceeding the release resistance determination value in step S5, the surface unit of the molded product is determined for each surface of the corresponding molded product. It is determined whether or not the release resistance value generated every time is within a predetermined release resistance determination value, and if it is within the release resistance determination value for all surfaces of the molded product, the release property is determined. Assuming that there is no problem, the gradient of the mold surface with respect to the mold release direction obtained in step S8 and the value of the mold surface state obtained in step S2 become design values as they are, and the process ends (step S9 in FIG. 2).

In step S9, when a release resistance value generated for each surface unit of the molded product obtained in step S8 exceeds a predetermined release resistance determination value, a corresponding surface of the molded product is determined. The surface is displayed on the three-dimensional shape model data (step S10). The state of the mold surface is changed for the surface of the molded product displayed on the three-dimensional shape model data as the surface exceeding the release resistance determination value in step S10 (step S11). The value of the mold surface state used for the change may be obtained from a data file such as a database of predetermined standard mold surface state values, or given by a person.

The slope value of the mold surface with respect to the mold release direction which is determined in step S7 and has no problem with the product function,
The value of the mold surface state determined in step 10, the mold release direction determined at the time of mold design, and the unit element generated on each surface of the molded product at the time of mold release start after mold opening determined in step S2. Calculation is performed again from the deformation amount and the deformation direction to obtain the release resistance in the changed surface state (step S12). In step S12, the surface exceeding the release resistance determination value is set to 3
With respect to the surface of the molded product displayed on the three-dimensional shape model data, the release resistance value generated for each surface unit of the molded product calculated again in step S12 is within a predetermined release resistance determination value. If so, it is determined that there is no problem in the releasability, and the gradient of the mold surface with respect to the mold release direction obtained in step S7 and the value of the mold surface state obtained in step S10 become the design values as they are.

Similarly, if there is a surface of the molded product displayed on the three-dimensional shape model data as a surface exceeding the release resistance determination value in step S10, the corresponding surface is determined for each surface unit of the molded product. It is determined whether the release resistance value generated in the mold release resistance is within a predetermined release resistance determination value, and if it is within the release resistance determination value for all surfaces of the molded product, it is determined that there is no problem with the release property. The gradient of the mold surface with respect to the mold release direction obtained in step S8 and the value of the mold surface state obtained in step S12 become design values as they are, and the process ends (step S13).

In step S12, if the surface of the obtained mold release resistance value generated for each surface unit exceeds a predetermined mold release resistance judgment value, the surface of the corresponding molded product is determined. It is displayed on the three-dimensional shape model data, returns to the design, and the shape is examined (step S14).

As described above, an example of the procedure for obtaining the optimum mold surface gradient with respect to the mold release direction and the optimum mold surface state has been described. It is easy to imagine that the present invention can be applied even when the calculation order is changed, such as determining an optimum mold surface gradient value in the direction.

[0023]

As described above, according to the mold designing method of the present invention, when designing the injection molding mold, the molded product comes into contact with the mold, so that the mold surface can be moved with respect to the mold release direction. It is possible to obtain a value that makes the gradient and the mold surface state appropriate. Moreover, the actual molding trial is not performed, and the gradient of the mold surface with respect to the appropriate release direction and the mold surface condition can be obtained more easily than in the past. Can be reduced.

[Brief description of the drawings]

FIG. 1 is a part of a flowchart showing a procedure for implementing a mold design method according to the present invention.

FIG. 2 is the remaining part of the flowchart shown in FIG. 1;

FIG. 3 is an example of a three-dimensional model of a molded product to which the present invention is applied.

FIG. 4 is a perspective view of a molding die.

FIG. 5 is a diagram illustrating a deformation amount generated for each unit element of a molded article and a vector indicating a deformation destination.

FIG. 6 is a diagram illustrating deformation vector data of a deformation amount and a deformation direction of a molded product.

FIG. 7 is a diagram showing an example in which a surface having poor releasability is displayed in three-dimensional shape model data.

FIG. 8 is a view showing an example in which a tip-shaped portion of a molded product functionally malfunctions by changing a slope surface in a releasing direction.

[Explanation of symbols]

 a Root thickness of surface to be graded b Thickness of tip of surface to be graded 4 Molding dies 1-8 Contact surface of dies

Claims (1)

[Claims] An analysis of filling, holding pressure, and cooling in an injection molding simulation is sequentially performed to determine a deformation amount and a deformation direction to be applied to each surface of a molded product at the time of starting mold release after opening a mold. From the amount of deformation and the direction of the deformation, the stress distribution caused by the mold in contact with the molded article restraining the molded article is determined. From the force, the gradient of the mold surface with respect to the mold release direction, and the mold surface condition, determine the mold release resistance that each surface receives, determine whether the mold release resistance is within a certain range, and if it does not fit, display that surface Further, the gradient of the mold surface and the mold surface state with respect to the mold release direction with respect to that surface are sequentially changed to obtain an appropriate gradient of the mold surface with respect to the mold release direction and an appropriate mold surface state. And mold design method.