JPH03224712A - Simulation of injection molding process and apparatus therefor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an injection molding process simulation W7 method and its apparatus, and in particular to a CAD (Coefficient) method for designing a molded product using thermoplastic resin or for designing a molding die. @put4r
Aictgtt Dazigk) system.

Molding process similane silane method suitable for calculating shape distortion such as warpage and non-uniform molding shrinkage of injection molded products and evaluating the suitability or unsuitability of molded product shape, metal structure, molding conditions, and molding materials, and its method It is related to the device.

[Conventional technology]

A typical conventional technology of a CAD system for designing an injection mold using thermoplastic resin as a molding material is the one described in MOLD FLOW, Plastics, Vol. 32 (1981), p. 51 (MOLD FLOW PTY, LTD. (hereinafter referred to as MOLD FLOIF') and Seaflow, Mold Technology, Volume 5 (1988), November issue, 999-10
Items described in 4 (A, C, manufactured by Tack, hereinafter C-FL)
OW') or Mold Cooling Analysis Program.

MoLd Cooling AnaLysis Pro
graph (manufactured by G, E, Inc.

(hereinafter referred to as MC4F) are known.

MOLD FLOW analyzes resin flow at the injection stage in the injection molding process, which consists of each stage of injection, holding pressure, and cooling. Useful for finding runner gate conditions to avoid weld lines in areas.

In addition, molding conditions related to molded product shape (size, shape, thickness, etc.) or injection conditions (resin temperature, mold temperature, injection time, injection pressure,
This is useful for finding out the stiffness force, etc.).

C-FLOII' performs resin flow analysis during the injection and holding pressure stages, and in addition to being as useful as MOLD FLOW', it also analyzes the appropriate molding conditions (holding pressure, holding time, etc.) during the holding pressure stage. Useful for finding out.

In addition, MCAP performs heat conduction analysis during the cooling stage of the injection molding process, and is used to achieve heat flow balance between the fixed mold and movable mold, and to find the placement and shape of mold cooling holes to shorten the molding cycle. , refrigerant temperature, and flow.

[A turtle trying to invent or solve a problem]

MOLD FLOW and C-FLOFF' of the above-mentioned conventional technology
is mainly used to evaluate the fluidity of resin, and MC
Since AP only evaluates heat conduction, it is directly related to shape accuracy, which is the most important aspect of molded product quality.
It was almost impossible to evaluate shape distortions such as warpage and non-uniform shrinkage.

In addition, as a prior art regarding shape distortion analysis of injection molded products, Plastics Ensuring Science, 22
Volume 4 (1982), pages 241 to 247, P
o13Hxar Eng@neering And S
scienceMarch, VoL, 22. A4
(1982), p. 241-247.

In this paper, an analysis method for "warp" deformation is presented, but the target shape is a --like thick plate, and "warp" deformation is defined as the point at which the center of the thickness reaches the glass transition temperature. The only method disclosed is an analysis method that calculates from the difference between the temperature distribution of the temperature distribution and the average temperature of the resin at that point in time. Furthermore, there was no disclosure of a method for calculating the "warpage" of molded products with complex shapes.

If the actual deformation of a molded product is a problem, it is necessary to analyze it using the difference between the temperature distribution during molding and room temperature. This is because, as long as deformation is calculated from the difference between the temperature distribution of the resin during molding and the average temperature, it is not possible to analyze molding shrinkage, and it is not possible to analyze the quality of molded products with respect to "warpage".

As mentioned above, in the conventional "warp" analysis method of molded products,
Unable to analyze “warpage” deformation and molding shrinkage of complex-shaped products,
There was a problem that realistic measures to improve the quality of molded products could not be taken sufficiently.

The plastic injection molding process involves injecting molten resin into a mold cavity under high pressure, holding pressure, and cooling it to solidify it, so flow and cooling are coupled, resulting in a phase change. It's a complex process. For this reason, although it has become possible to predict the optimal conditions for the injection stage during the molding process by using flow analysis programs such as MOLD FLOW and C-FLOW, conventionally, in general, the The mechanisms that cause "warpage" and uneven shrinkage are considered to be a black box, and the manufacturing conditions related to the shape accuracy of plastic molded products, including high-precision parts, are determined by manufacturing molds based on experience and intuition and repeating trials. However, there was a problem in that the time and cost required for the development and design of high-precision parts increased.

Against this background, the imageability of simulation systems that calculate the uneven conditions of "warpage" and molding shrinkage and evaluate the suitability and unsuitability of molded product shape, mold structure, molding conditions, and molding materials has increased. ing.

For this reason, in recent years, research into analysis methods for ``warpage'' has begun to be conducted both in Japan and abroad.

However, since the "warpage" and uneven molding shrinkage conditions of injection molded products are caused by the entire injection molding process consisting of each stage of injection, holding pressure, and cooling, it is necessary to analyze "warpage" and uneven molding shrinkage. It is considered necessary to perform injection flow analysis, packing pressure analysis, and thermal stress strain analysis. In the injection flow analysis, the resin can be analyzed as being incompressible, so the analysis can be performed in a relatively short calculation time. On the other hand, in a packing pressure analysis, it is necessary to take into account the pressure dependence of specific volume, which is a physical characteristic of thermoplastic resin, so in a strict analysis of packing pressure, the resin is solved as compressible. Therefore, it is unavoidable that a huge amount of calculation time is required for the packing pressure analysis.

This is a major problem when calculating non-uniform shrinkage from the above-mentioned injection flow analysis, packing pressure analysis, and thermal stress strain analysis.The present invention solves the problems in the prior art described above. This was done for the purpose of calculating the "warpage" and non-uniform shrinkage of molded products, and rigorous analysis is required for the injection flow analysis - packing pressure analysis - packing pressure analysis during thermal stress strain analysis. By simply calculating the holding pressure conditions, you can calculate the shape distortion of the molded product such as "warpage" and uneven shrinkage that occur during the molding process, and calculate the shape of the molded product, metal structure, molding conditions, molding material, etc. We evaluate the effects of molding on shape distortion prior to metal production, select appropriate conditions, and develop molded products.

It is possible to reduce the design time and cost,
It is an object of the present invention to provide a shimmy resin injection molding process and an apparatus therefor.

[Means to solve the problem]

In order to achieve the above objectives, in a molding process simulation that evaluates the metal structure, molded product shape, molding conditions, molding material, etc., at least the injection flow analysis regarding the injection stage and the temperature of the molding material at the end of the injection stage are conducted. The distribution and pressure distribution are calculated, and the temperature distribution at the end of the injection stage is used as an initial value to calculate the temperature change of the molding material during the holding pressure and cooling stage after injection. From the temperature change of the molding material, the molten phase of the molding material is calculated. Calculate the change in the connection of the molten phase, find the temperature distribution of the molded part at the change in the connection of the molten phase, and use this temperature distribution and the pressure distribution at the end of the injection stage calculated from the injection flow analysis.

Thermal stress strain analysis is performed to calculate thermal stress strain, and shape distortion of the molded product such as "warpage" and uneven shrinkage is calculated from the displacement related to this thermal stress strain.

In addition, in the molding process simulation that evaluates the mold structure, molding conditions, molded product shape, molding material, etc. , a second means for calculating the temperature change of the molding material in the holding pressure-cooling stage after the injection stage using the temperature distribution at the end of the injection stage calculated by the first means as an initial value; From the temperature change of the molding material calculated from A fourth means for calculating thermal stress strain using the temperature distribution at which the connection of the molten phase changes and the pressure distribution at the end of the injection stage obtained from the first means, and calculating from the fourth means. This method calculates the shape of the molded product, such as 1 warpage and non-uniform shrinkage, from the displacement.

[Effect]

Thermoplastic resins are in a fluid, molten state at high temperatures, but when the temperature drops, they lose their fluidity and enter an eigenstate. The transition temperature at which a thermoplastic Il (fat) changes from a flowing molten state to a solid state where it loses fluidity is expressed as the flow stop temperature.For example, the flow stop temperature of methacrylic resin is approximately 170°C.
℃, and the flow stop temperature of polycarbonate resin is approximately 1
The temperature is 90°C.

The injection molding process consists of an injection stage in which high-temperature, molten resin is injected into the mold cavity, and a pressure holding stage in which the injection pressure is maintained in the mold even after the molten resin has been injected into every corner of the cavity. The process consists of a cooling stage in which the molded product is kept cooled until it is taken out from the mold after holding pressure, and a sinking stage in which the molded product is taken out from the mold.

The pressure holding stage of injection molding is carried out simultaneously with cooling, and the molding inside the cavity is carried out using the connection of the high temperature molten phase inside the resin in the flow paths of the mold such as the runner gate and cavity. This is an operation in which additional resin is supplied to compensate for the volumetric shrinkage that occurs as the material cools. Even if the temperature decreases due to cooling, as long as the resin is supplied, molding shrinkage will not occur in the molded product.

Therefore, the molded product in the mold, which is in the holding pressure stage where the resin is not being replenished and is being cooled at °C, is treated as being cooled at the upper limit of the linear expansion coefficient in the mathematical-physical model used for analysis. Expression is allowed.

In injection molding, which uses thermoplastic resin as the molding material,
As the cooling progresses, the connection between the molten phase 1 inside the resin is eventually severed, and as a result, there always occurs a point where the supply of resin to compensate for molding shrinkage due to cooling stops. From the point at which the resin replenishment fails, the downstream portion of the part is cooled under conditions of constant mass, so cooling shrinkage, that is, molding shrinkage, starts.

In the present invention, the injection molding process is targeted by a first means of analyzing resin flow at the injection stage.

Temperature distribution and pressure distribution at the end of the injection stage)
Using the temperature distribution at the end of the injection stage obtained from the above means as an initial condition, the temperature change of the molding material during the holding pressure-cooling stage after the injection stage is calculated by the second means for temperature analysis, and the second means Using the temperature change of the molding material after the injection step obtained by Determine whether the temperature has reached the flow stop temperature of the resin, identify changes in the connection of the molten resin phase in each part of the molded product, and determine the point at which resin replenishment stops and molding shrinkage begins. Calculate 0 then, using the change in the melt phase connection of the molding material, the point at which the molding shrinkage obtained by means of the molding material begins,
The resin temperature distribution is determined from the calculation results of the second means for calculating the temperature change of the molding material after the injection stage. Furthermore, the temperature distribution of the molded product at the time when molding shrinkage starts, the pressure distribution at the end of the injection stage obtained by the first means, and the time during which the molded product is molded from the mold and becomes room temperature-like under atmospheric pressure. The thermal load condition determined by the temperature difference and the pressure difference is calculated, and the thermal stress strain is calculated using the fourth means of thermal stress strain analysis using this thermal shock 1 condition, and the thermal stress strain is calculated for each part of the molded product during the molding process. Calculate shape distortion of molded products such as warpage and uneven shrinkage caused by uneven temperature and pressure distribution.

Next, the present invention will be explained in detail with reference to FIG.

FIG. 2 is a schematic diagram of the injection molding process. Su, +11
indicates the movement of the resin in the mold at each stage: injection, (2) holding pressure, (3) cooling, and (4) release.The arrows in the figure indicate the direction of pressure or the movement of resin Indicates flow direction. "Also, the boundary line between the molten phases A, A' and the solidified phase B is the temperature line when the resin stops flowing.

FIG. 2 (1) shows the injection stage of injecting the resin P into the gold cavity C from the gate G. Next, in the pressure holding stage shown in FIG. As long as the gate G is connected to the molten phase a′ in
Due to the holding pressure at , the molten phase a.

A slight resin flow occurs in the arrow direction within α' to compensate for the cooling shrinkage of the resin P, and the volumetric shrinkage of the 541 resin P due to cooling is replenished as a flow path connecting the molten phases α and α'.

As the cooling progresses, a solidified phase develops, and the connection between the molten phases α and a' is severed, as shown by the blank in FIG. 2 (2).

Then, the supply of resin P is cut off, and from that point onwards.

Downstream of the point where the resin supply is cut off, that is, at the corner, cooling occurs under conditions where the mass is constant, and molding shrinkage begins.

Therefore, in the part where the gate G is thinner than the part where the gate G is installed, and the inside part cools and solidifies first, the maximum temperature inside the part reaches the flow stop temperature.
In the part where the gate G is thicker than the part where the gate G is provided, and the inside cools and solidifies later, the resin will not flow even if the temperature decreases until the maximum internal temperature at the part where the gate G is provided reaches the flow stop temperature. When cooling after the resin supply is cut off, the parts downstream of the point where the resin supply is cut off are cooled under conditions where the mass is constant, and molding shrinkage therefore begins.

What is the specific volume of thermoplastic resin used in injection molding?

Pressure (
P) - Specific volume (1) - Temperature (T).

Therefore, when the molded product is released from the mold and the temperature becomes uniform under atmospheric pressure, the change in the specific volume of each part of the molded product is completed. Therefore, molding shrinkage is complete when the molded product is released from the mold and the room temperature becomes uniform under atmospheric pressure. The distribution causes a "warp" deformation.

Deformation due to temperature drop is a phenomenon governed by the law of thermal stress-strain relationship, and can be analyzed by thermal stress-strain analysis. In addition, expansion and contraction associated with pressure changes are phenomena governed by the P - v - T relationship of the specific volume of thermoplastic resin, and P
- This is a phenomenon that can be analyzed from the C-T relationship. Hence, the "warp" of injection molded products.

Shape distortion such as non-uniform shrinkage is caused by P of the specific volume of thermoplastic resin.
-w - It can be calculated from thermal stress strain analysis considering T dependence.

〔Example〕

Below, each embodiment of the present invention is shown in Fig. 1 and Fig. 5 to t1.
．． This will be explained with reference to FIG.

FIG. 1 is a block diagram showing the configuration of a molding process and shim removal system according to an embodiment of the present invention.

Fig. 3 is a schematic diagram showing the change in pressure at a certain point within the cavity over time, Fig. 4 is a diagram showing the distribution of the pressure in the cavity over time, and Fig. 5 shows the pressure, specific volume, and pressure of the resin. FIG. 3 is a diagram showing the relationship between temperatures.

In FIG. 1, 1 is an input device, and represents a node coordinate 1 node number that expresses the shape of a mold or molded product.

Input data for injection flow analysis such as shape data of element numbers, boundary conditions such as resin flow velocity and resin temperature at mold inlet, mold temperature, viscosity data consisting of relationship with shear rate and temperature, thermal conductivity and specific heat Input data for calculating melt phase break point, such as resin flow stop temperature, and input data such as molding machine mold clamping force, molded product projected area, pressure gradient coefficient, minimum pressure constant, etc. for simplified calculation of molding shrinkage start pressure, which will be described later. In addition to creating a P-v-T take for calculating the converted temperature distribution at the start of molding shrinkage, which will be described later, and an input take for thermal stress strain analysis consisting of restraint conditions, Young's modulus, coefficient of linear expansion, Boann ratio, etc. The above-mentioned each pole data is sent to the input data storage device 2. Note that the metal temperature, thermal conductivity, and specific heat are also used as input data for temperature analysis after the injection stage.

5 is the resin flow rate at the injection stage of injection molding.

This is an injection flow analysis device that solves changes in temperature and pressure force, and uses the shape data in the input data storage device 2 and the input data for injection flow analysis described above to fill the cavity with resin to every corner from the start of injection. The temperature and pressure changes of the molding material up to the injection end point are calculated, and the calculation results are output to the injection flow storage device 4.

Next, the post-injection temperature analysis device 5 uses the input data for temperature analysis stored in the input data storage device 2 and the temperature at the end of the injection stage in the injection flow storage device 4 as initial values, and The subsequent changes in resin temperature over time are solved, and the calculated results are output to the temperature storage device 6 after injection.

7 is a melt phase break point calculation device, and an input data storage device 2
The internal maximum temperature of each part of the molded product reaches the flow stop temperature using the flow stop temperature in The time point reached is calculated and output to the melt phase break point storage device 8.

Next, for each part of the molded product, the molding shrinkage start point calculation device 9 compares the point at which the flow stop temperature is reached inside the point of interest and the inside of the upstream valley from the point of interest to the entrance of the mold, and determines whether the upstream point is earlier than the point of interest. When the flow stop temperature is reached, the time when the flow stop temperature inside the upstream part is reached is the time when molding shrinkage starts in each downstream part from the upstream part. Furthermore, when the point of interest reaches the flow stop temperature before the upstream parts, the time point when the inside of the point of interest reaches the flow stop temperature is the point at which molding shrinkage of each part downstream from the point of interest starts.

In this way, the time point at which molding shrinkage starts for each part of the molded product is calculated, and the results are output to the molding shrinkage start pressure storage device 10.

Reference numeral 11 denotes a molding shrinkage start temperature calculating device related to the temperature distribution calculating means at the time of starting molding shrinkage, which brings temperature information of each part of the molded product at the starting point of molding shrinkage from the injection flow storage device 4 or the temperature storage device 6 after injection. The temperature is then output to the molding shrinkage start temperature storage device 12.

Reference numeral 13 denotes a molding shrinkage start pressure simple calculation device which is a simple calculating means for pressure distribution at the start of molding shrinkage, and stores the molding machine clamping force, molded product projected area, pressure gradient coefficient, minimum pressure constant, etc. in the input data storage device 2. Then, the pressure distribution in the molded product at the end of injection in the injection flow storage device 4 is brought from the injection flow storage device 4, and the pressure distribution at the start of molding shrinkage is simply calculated by the method described below, The molding shrinkage start pressure is output to the memory device 14.

The principle and simple calculation method of the pressure distribution at the start of molding shrinkage will be explained.

The resin pressure inside the mold is applied from the molding machine,
The pressure in the molding machine is higher than the pressure inside the mold.The pressure inside the mold during injection flow is a dynamic pressure, but in the pressure holding stage after the injection is finished, the pressure inside the mold becomes hydrostatic pressure. For this reason, the resin pressure inside the mold rises rapidly after the injection is finished, and as shown in Figures 3 and 4, the resin pressure inside the mold is higher than the pressure at the end of the injection at the pressure holding stage. After that, the resin temperature decreases due to cooling and the viscosity increases,
As the pressure loss increases, the pressure decreases, and as cooling and solidification progresses, the pressure within the mold decreases.

In the injection and pressure holding stages, if the calculated value of (average value of pressure inside the mold) To set the molding pressure, (average pressure inside the mold during the injection or pressure holding stage) is set within a range that does not exceed (molding machine mold clamping force F)/(projected area S of the molded product).

From the above, in actual molding, the resin pressure in the mold is set within a range where the following equation holds, where the average pressure at the end of injection is expressed as 7:1 and the average pressure during the pressure holding stage is expressed in Ph. be done.

P@≦Ph5F ÷ S...
・・・・・・・・・・・・ +11 Here, α is a coefficient related to the pressure gradient, b is a constant representing the lowest pressure in the mold during the pressure holding stage, and Ph is approximated by a linear equation of 7;1. The following equation is obtained.

Ph = αp(+b...
・・・・・・・・・・・・・・・・・・・・・・・・
...+21 Substituting equation (2) into equation (1) yields the following equation.

Applying the relationship in equation (2) to the pressure at any point within the cavity (mold), the pressure at any point within the cavity at the end of injection is represented by Pt, and the pressure at the pressure holding stage is represented by II. The following equation is obtained.

PA=αp6+b・・・・・・・・・・・・・・・
・・・・・・・・・・・・－・・・・・・・・・(41(
In equation 2), h (minimum pressure within the entire mold during the pressure holding stage) is usually on the order of several tens to 300%. The pressure Pt inside the mold at the end of injection is brought from the injection flow storage device 4 and is set to P4.
By calculating and substituting b into equation (3), the possible range of values for α is determined. By substituting α, b determined in this way and Pt brought from the injection flow storage device 4 into equation (4), it is possible to roughly estimate the range of values that Ph can take during the pressure holding stage. , II = 200%,
S = 200cIA, F = 150000ke
, b = o ~ 200 From equation (3), α = 0 ~ 6.7
Possible values range from 5 to 5. In the pressure holding stage, the cooling of the resin is more advanced than in the injection stage, and since the viscosity of the resin is high and the pressure gradient inside the mold is large, α≧1.0 in equation (4) is often greater. Therefore, α=1.0-5.75 is the most possible cage.

Returning to the explanation of FIG. Reference numeral 15 denotes a molding shrinkage start temperature conversion device which converts the temperature information in the molding shrinkage starting temperature storage device 12, the pressure information in the molding shrinkage starting pressure storage device 14, and the p- stored in the input data storage device 2. Using the v-r data, the temperature under molding pressure at the start of molding shrinkage is converted to the temperature under atmospheric pressure using the method described in the following.

As shown in Figure 55. On the P-U-7' data, the specific volume is determined by giving pressure and temperature. In Figure 5,
Let the pressure at the start of molding shrinkage be P, the temperature be T, the specific volume V determined by this pressure P and temperature T, and the temperature at which the pressure is atmospheric pressure P' and the specific volume V be Tc. As shown in Fig. 5, pressure P, specific volume V determined by hot water temperature, and atmospheric pressure P'
, the difference from the specific volume V' determined by the temperature T' is the atmospheric pressure P',
This is the same as the difference between the specific volume &V determined by the temperature Tc, the atmospheric pressure p', and the specific volume V' determined by the temperature of the chamber.

Assuming exaggeration, the molding shrinkage rate is 1-(11'/ν)l/S. Therefore, if pressure, specific volume, and temperature data are used, and pressure P and temperature T are given, the molding shrinkage rate is the same. The temperature rc1 under the atmospheric pressure P' can be calculated as follows.

By using this relationship, the resin temperature at the start of molding shrinkage, which was T under molding pressure P, can be converted to the value under atmospheric pressure by considering the pressure dependence of 1 m fat specific volume at the start of molding fil. The temperature at the time Tc is determined for each part of the molded product and outputted to the molding shrinkage start conversion temperature storage device 16.

Reference numeral 17 denotes a thermal stress strain analysis device that analyzes thermal stress, such as shape data, Young's modulus, Poisson's ratio, line number, constraint conditions, and temperature information stored in the temperature correction storage device 16, stored in the input data storage device 2. Using the input data for strain analysis, calculate the displacement of the molded product from thermal stress strain analysis using the temperature difference between the converted temperature at the start of molding shrinkage stored in the converted temperature storage device 116 and room temperature as the thermal load condition. Then, the calculation result is outputted by the output device 18.

The output displacement of the molded product reveals the "warpage" and uneven shrinkage of the molded product that occur due to uneven temperature and pressure during the molding process.

Next, FIG. 6 is a block diagram showing the configuration of a molding process simulator system according to a second embodiment of the present invention.

In the drawings, the parts shown in FIG. 1 and those marked by numerals are the same as those in the embodiment shown in FIG. 1, respectively.

The explanation will be omitted.

The embodiment shown in FIG. 6 has 11 configurations that further simplify the calculation compared to the embodiment shown in FIG. This embodiment differs from the embodiment shown in FIG. 1 in that the molding shrinkage start pressure memory device 14 is not provided.

In the description of the embodiment shown in FIG. 6, only the points different from the embodiment shown in FIG. 1 will be explained.

In the embodiment shown in Figure IK1, the molding shrinkage start temperature clamp X device 15
When calculating the converted temperature under atmospheric pressure at the start of the molding section Jll, use the temperature information in the molding shrinkage start temperature storage device 12 and the pressure information in the molding shrinkage start pressure storage device 14, etc.
The temperature under molding pressure at the start of molding shrinkage was converted to the temperature under atmospheric pressure.

On the other hand, in the embodiment shown in FIG. 6, when calculating the converted temperature under atmospheric pressure at the time of starting molding shrinkage with the molding shrinkage start temperature conversion device 15, the temperature information in the molding shrinkage start temperature storage device 12 and the injection flow storage device are used. Using the pressure information at the end of injection in 4, the temperature under molding pressure at the start of molding shrinkage is converted to the temperature under atmospheric pressure. This is the only difference from the embodiment shown in FIG. 1, but the other processing is the same as the embodiment shown in FIG.

According to the example shown in Figure 6, the effect of the pressure distribution during the holding pressure stage during the molding process is not included in the "warpage" calculation, so the calculation accuracy is inferior to the example shown in Figure 1, but the molding shrinkage rate Since the influence of pressure on is much smaller than the influence of temperature, it is useful to use a ``seven-ri'' calculation that reduces calculation time and calculation cost even more than the embodiment shown in FIG.

Next, FIG. 7 is a block diagram showing the configuration of a molding process simulation system according to an embodiment of WJ6 of the present invention. Components in the figure with the same reference numerals as in FIG. 1 are equivalent parts, so their explanation will be omitted.

The embodiment shown in FIG. 7 is similar to the embodiment shown in FIG. The “sled” I got
Compare the value of deformation and the design allowable value, and if the value exceeds the design allowable value,
a judgment device 19 that issues a warning when "warpage"occurs; a new acid type condition setting device 20 that changes molding conditions such as metal temperature, resin temperature, and injection speed ring; This device is equipped with a new molded product shape setting device 21 that changes the molded product and metal shape.

From the input device 1 for setting input data to the output device 18. "Warpage" calculated by the same process as the example in Figure 1
is determined by the determining device 19 to be inappropriate.

New acid type condition setting device 20. Alternatively, the new molded product shape setting device 21 creates new acid type conditions and new molded product shape data.

This result is fed back to the input device 1.

The "warp" deformation is calculated again. And 9 judgment iron amount 19
The process is repeated until the calculation result is determined to be acceptable.

The new acid form conditions and the method for creating new molded product shape data were specified in advance at the time of data entry. Depending on the factors of molding conditions and molded product shape, or the extent of the difference between the calculated warpage deformation and the design tolerance [Automatically selects the molding conditions and molded product shape factors and selects 1 (or selects one in advance) This can be achieved by automatically and step-by-step changing the values of the calculated factors according to the degree of the difference between the calculated "warp" deformation and the design tolerance.

The above change factors for generating new acid form conditions and new molded product shape data are related to molding conditions.

Mold temperature difference between the front and back sides of the molded product, injection speed.

These include the tung fat temperature, the clamping force of the molding machine, and α and b in equation (4). Also, regarding the shape of the molded product.

These include the gate position, the thickness, length, and angle of the part specified in advance during data input in the molded product.

Optimization of the molded product shape and molding conditions is achieved by the following method. Compare the calculated value of the new "warp" using the new acid form conditions and new molded product shape data created by the above method with the calculated value of the "warp" calculated at the beginning or previously, and then calculate the new "warp". If the calculated value of ``warp'' has decreased compared to the previously calculated value of ``warp,'' then either the new calculated value of ``warp'' is less than or equal to the design allowable value, or the minimum value of the new total 311 values of ``warp.'' Perform calculations for the same change factor until . In addition, we have developed a new "
Compare the total value of ``sled'' with the calculated value of ``sled'' calculated at the beginning or earlier, and find out that the new ``7ri'' calculation i1 has increased compared to the previously calculated ``sled'' value. In this case, the direction of change of the change factor is corrected during the primary calculation. (For example, 4
11 Increase the fat temperature [calculate, if "warp" increases,
Decrease the resin temperature in the next calculation. ) Also, iF
rMolding conditions.

Calculated values for the new "Sevenari" using the new molded product shape.

Compare the calculated value of "warp" calculated at the beginning or earlier, and if the "warp" is greater than the significant difference set in advance when inputting the data.
When the new calculated value of does not change.

The next time new data is generated, another change factor is selected and new data is generated. (For example, even if you change the gold temperature difference between the front and back sides of the molded product.

If the "curvature" does not change beyond a significant difference, the gate position is changed in the next calculation. ) The above methods are
By applying the well-known forging optimization method of damped forging,
Molded product shape that satisfies standard values related to design tolerances, gold m*
The combinator can automatically search for manufacturing and molding conditions.

The configuration of the "warp" deformation calculating section shown within the dotted line in FIG. 7 is the same as the embodiment shown in FIG. 1, but it goes without saying that the embodiment shown in FIG. 6 can be applied to this part.

'Also. In the injection flow analysis, post-injection temperature analysis, and thermal stress strain analysis in each of the above examples, the finite element method is used.The reason is that the finite element method simplifies the shape of the object to be analyzed. This is because it is the method that allows the analysis to be carried out with the least number of problems and with high accuracy.The above-mentioned analyzes are not limited to analysis using the finite element method, but may also be performed using other numerical methods such as the finite difference method or the boundary element method. do not have.

In addition, in the embodiment shown in FIG. 1 above, when calculating the pressure PL in the holding pressure stage from the pressure P6 at the end of injection, it was calculated from equation (4), but when calculating Ph from Pl, the equation is ( 4
), but the relationship between PA and P4 is as follows:
It may include factors such as distance from the gate, cooling time, and viscosity.

Here we will discuss the effects of a specific example in which the embodiment shown in Figure 1 is applied to an injection molded product using thermoplastic resin. 1t
814.

Figure 8 shows an injection molded product made of acrylic resin that has a cylindrical depression in the center of the box shape, and has a uniform thickness of 2.0 mm.
A gate is provided at the bottom of the central cylindrical part.

As a result of calculating the "warpage" deformation by applying the embodiment shown in FIG. 1, it was found that "warp" of -150 to -250 μm was generated on the upper surface. - means that the warp occurs in the direction in which the warp is concave with respect to the shape of the metal cavity, and + means that the warp occurs in the direction in which the warp is convex with respect to the shape of the cavity.

Figure 9 shows calculations made by changing the gate position in order to reduce the "warpage" of the molded product shown in Figure 8. By moving the gate position from the bottom of the central cylindrical part to the top surface, Temperature unevenness and pressure unevenness within the molded product at the start of molding shrinkage can be averaged out, and the warpage on the top surface can be reduced by -25μ.
It has been found that the shape accuracy of the molded product can be significantly improved, with a decrease of 30 μm to +30 μm.

As described above, according to the molding process stains in the embodiment shown in FIG. Uneven shrinkage can be calculated prior to gold fabrication or molding experiments.

It has the great effect of being able to evaluate and optimize the metal structure of the gate position, the shape of the molded product, and the molding conditions in a short period of time when starting mold design.

゛Again. This eliminates the need to create molds based on experience and intuition, as in the past, and then change the molded product shape, gate position, and other metal structures through trial and error. This eliminates the need for the development and design of plastic parts or molds. The period and cost of mourning can be significantly reduced.

Furthermore, since the molded product shape, mold structure, and molding conditions can be optimized and manufactured, molded products having desired characteristics can be manufactured with high yield.

Incidentally, it goes without saying that the molding process shimieration charts of the embodiments shown in FIGS. 1, 6, and 7 can be used in a design CAD system for molded product design or molded metal design. In addition, the molding process simulations of the embodiments shown in Figures 1, 6, and 7 above are used as an accessory device of an injection molding machine to calculate the "seven warping" and non-uniform molding shrinkage of the molded product. Needless to say, it is used as a means to issue warnings and optimize the suitability of conditions, molded product shape, metal structure, etc.

〔Effect of the invention〕

According to one aspect of the present invention, as described in detail above.

Calculate shape distortions of molded products such as "warpage" and non-uniform shrinkage caused by the molding process, and evaluate molded product shape and metal structure.

The influence of molding conditions, molding materials, etc. on shape distortion.

It is possible to provide a molding process similation method and an apparatus therefor, which can evaluate and select appropriate conditions prior to metal production, thereby reducing the time and cost required for development and design of molded products.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a molding process and milling system according to an embodiment of the present invention. Fig. 2 is a schematic diagram of the injection molding process, Fig. 3 is a schematic diagram showing the change in pressure at a certain point within the cavity over time, Fig. 4 is a diagram showing the distribution of the pressure in the cavity with respect to changes over an hour, and Fig. 5 6 is a diagram showing the relationship between resin pressure and specific volume of 1 m degree, FIG. 6 is a block diagram showing the configuration of a molding process shimmy seal system according to another embodiment of the present invention, and FIG.
The figure is a block diagram showing the configuration of a molding process simulation system according to the third embodiment of the present invention, and FIG. The explanatory diagram shown in FIG. 9 is an explanatory diagram showing "warpage" of the injection molded product of FIG. 8 with the gate position changed. 1...--...Input device 2...Input data storage device 6...
・・・・・・－・・・・Injection flow analysis device 4・・・・・・
・・・・・・Injection flow storage device・・・・・・・・・・・・
・Temperature analysis f device since injection・・・・・・・・・Temperature storage device after injection・・・・・・・・・ Melt phase break point calculation device・・・・・・・・・・・・...Melting phase break point storage device...Molding shrinkage start point calculation device...Molding shrinkage start point storage device...・・Temperature calculation device at the start of molding shrinkage・・
...Temperature storage device at the start of molding shrinkage...
...Simple calculation device for pressure at the start of molding shrinkage...
...Simplified pressure memory device at the start of molding shrinkage...
・・・・・・Molding shrinkage start temperature conversion device・・・・・・・・・
・Molding shrinkage start conversion temperature storage device・・・・・・Thermal stress strain analysis device・・・・・・Output device

Claims (1)

[Claims] 1. In an injection molding process simulation method for evaluating resin molding conditions, molded product shape, molding material, mold structure, etc., the temperature change and pressure of the molding material at least at the injection stage are determined by injection flow analysis. After calculating the change, calculate the temperature change of the molding material after the injection step by temperature analysis, calculate the point at which the molten phase of the molding material is disconnected from the temperature change, and calculate the temperature change of the molding material at that point. Calculate the thermal stress strain of the molded product using the temperature distribution and the pressure distribution of the molding material at the end of the injection stage determined from the injection flow analysis, and calculate the shape distortion of the molded product from the amount of displacement related to the thermal stress strain. An injection molding process simulation method characterized by: 2. If the average pressure inside the mold at the end of the injection stage determined from the injection flow analysis is less than the average pressure inside the mold at the end of the injection stage, calculate (molding machine mold clamping force) / (molded product projected area). 2. The injection molding process simulation method according to claim 1, further comprising: calculating the thermal stress strain using the corrected pressure value after correcting the pressure value to be equal to or less than the corrected pressure value. 5. When the pressure at any point in the mold at the end of the injection stage is P_i, the average pressure inside the mold is P_i, the holding pressure stage pressure P_A, the clamping force of the molding machine is F, and the projected area of the molded product is S. , 1-b/@P@_i≦a≦F/S・1/@P@_i-b
/@P@_i, a coefficient a related to the pressure gradient, a constant b representing the lowest pressure in the mold during the pressure holding stage, and P
Holding pressure stage pressure P_ determined by the formula _A=aP_i+b
2. The injection molding process simulation method according to claim 1, wherein thermal stress strain is calculated using A. 4. In an injection molding process simulation device that evaluates resin molding conditions, molded product shape, molding material, and mold structure, the first step calculates temperature changes and pressure changes of the molding material at least at the injection stage by injection flow analysis. A second means for calculating the temperature change of the molding material after the injection step by temperature analysis using the temperature distribution of the molding material calculated from the first means as an initial value; and the second means. a third means for calculating the point at which the connection between the molten phase of the molding material is broken using the temperature change of the molding material calculated from the temperature change of the molding material obtained from the third means and the second means; a fourth means for calculating thermal stress strain using the temperature distribution of the molded article at the time when the phase connection is severed and the pressure distribution of the molding material at the end of the injection stage obtained from the first means; An injection molding process simulation device comprising: calculating shape distortion of a molded product such as "warpage" and non-uniform shrinkage from the displacement calculated by the fourth means. 5. The first means, the second means, and the third means, and the average pressure within the mold at the end of the injection stage obtained by the first means is the same as the average pressure in the mold at the end of the injection stage. a fourth means for correcting the pressure to be equal to or higher than the average pressure within and equal to or less than the calculated value of (molding machine mold clamping force)/(molded product projected area); and a molding obtained from the second means and the third means. Using the temperature distribution of the molded product at the time when the connection between the molten phases of the material is broken and the corrected pressure distribution obtained from the fourth means, the temperature distribution of the molded product at the start of molding shrinkage is determined under atmospheric pressure. and a sixth means for calculating thermal stress strain using the temperature distribution at the start of molding shrinkage obtained and converted from the fifth means,
An injection molding process simulation device characterized in that the shape distortion of the molded product, such as "warpage" and non-uniform molding shrinkage, is calculated from the displacement calculated by the fifth means. 6. The first means, the second means, and the third means, the average pressure in the mold at the end of injection is @P@_i, and the average pressure in the mold at the pressure holding stage is @P@_A , when the mold contraction force of the molding machine is F and the projected area of the molded product is S, 1-b/@P@_i≦a≦F/S・1/@P@_i-b
Coefficient a related to pressure gradient determined from the formula /@P@_i
and a constant b representing the lowest pressure in the mold during the pressure holding stage, and when the pressure at any point in the mold at the end of the injection stage obtained from the first means is P_i, P_A=aP_
a fourth means for calculating the pressure P_A determined from the formula i+b; a temperature distribution of the molded article at the time when the connection between the molten phases of the molding material obtained from the second means and the third means is severed; a fifth means for converting the temperature distribution at the start of molding shrinkage of the molded article into a value under atmospheric pressure using the pressure P_A obtained from the fourth means; and a molding obtained and converted from the fifth means. and a sixth means for calculating thermal stress strain using the temperature distribution at the start of contraction,
An injection molding process simulation apparatus characterized in that shape distortion of the molded product, such as "warpage" and non-uniform shrinkage, is calculated from the displacement calculated by the sixth means. 7. A design CAD system device comprising the device according to any one of claims 4 to 6. 8. Means for comparing the "warpage" and non-uniformity of molding shrinkage of the molded product calculated by the apparatus according to any one of claims 4 to 6 with a reference value; A design CAD system device characterized by comprising means for feeding back non-uniform shrinkage and setting resin molding conditions, molded product shape, mold structure, etc. 9. An injection molding machine comprising the apparatus according to any one of claims 4 to 6. 10. "Warpage" of a molded product calculated by the apparatus, comprising the apparatus according to any one of claims 4 to 6;
Equipped with a means for comparing non-uniform molding shrinkage with a reference value, and a means for feeding back the "warpage" and non-uniform molding shrinkage of the molded product to optimize resin molding conditions, molded product shape, mold structure, etc. Injection molding machine.