JP2003340898A - Method for calculating pressure history of tip of nozzle in consideration of characteristic of molding machine, method for simulating injection molding, and its program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means for calculating conditions for simulating an injection molding process by estimating the pressure history of the tip of a nozzle from the set value of an injection molding machine in consideration of the problem that although it is necessary to allot analytical conditions to a resin inflow opening when the injection molding process is simulated, since there is a large difference between an injection pressure and a nozzle tip pressure, it is difficult to allot correct conditions. <P>SOLUTION: The means includes a part 1 which measures the relationship between the set value of the injection molding machine and the nozzle tip pressure in advance and calculates the pressure history of the tip of the nozzle from the set value and part 2 which simulates a molding including a sprue runner by allotting the pressure history of the tip of the nozzle in the resin inflow opening as the molding conditions to a model for simulating the injection molding process. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention generally relates to molding using an injection molding machine.

[0002]

2. Description of the Related Art In an injection molding die, if the resin cannot be filled in the entire cavity unless the filling pressure is increased, the injection speed of the speed control type injection molding machine is set high, resulting in a high filling pressure. Thus, the injection speed is set so that the cavity is easily filled with the resin. On the other hand, when performing a simulation of the injection molding process (simulation of a series of molding processes such as flow, holding pressure, cooling and warpage prediction), the molded product and sprue runner are modeled and the flow rate or filling time of the resin inlet is set Then, the filling pressure was predicted. As described above, since the setting place and the condition are different between the simulation and the condition of the actual molding machine, it is necessary to estimate and input the condition of the resin inlet for the simulation.

[0003]

With an actual molding machine, the injection pressure generated during molding can be monitored.
There is a big difference between this value and the pressure value of the resin inlet, and if the molding machine and cylinder are different, the difference also differs.Therefore, set the resin inlet conditions correctly for the simulation of the injection molding process. It was difficult to do. Therefore, even if the injection molding process was simulated, a large error in condition estimation of the resin inlet was included, and the absolute value thereof was unreliable, so only qualitative evaluation could be performed.

[0004]

The present invention has been made to solve the above problems, and comprises a molding machine characteristic measuring section, a molding machine characteristic calculating section, and an injection molding process simulation section.

The molding machine characteristic measuring unit uses a molding machine and a cylinder that are actually used, and a mold having a pressure sensor installed near the resin inlet is used to measure the injection pressure history of the molding machine using the resin temperature and the injection speed as parameters. A part for measuring the pressure history near the resin inlet.

The molding machine characteristic calculation unit subtracts the pressure loss amount according to the injection pressure and the pressure loss amount according to the combination of the molding machine and the cylinder from the injection pressure history of the molding machine obtained by the molding machine characteristic measurement unit. Is a part for calculating the pressure history of the nozzle tip.

The injection molding process simulation section
Modeling the sprue, runner, and molded product parts,
This is the part that analyzes cooling and warpage deformation.

When the molten resin temperature and the injection speed are set, the pressure history at the resin inlet is calculated by the molding machine characteristic calculation section. By using the calculated pressure history of the resin inflow port as an analysis condition and performing an analysis by the injection molding process simulation unit, an analysis result that can be quantitatively compared with the actual molding can be obtained.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The details of the present invention will be described below with reference to examples. FIG. 1 is a diagram showing the flow of the present invention.

Reference numeral 1 is a molding machine characteristic measuring section. As shown in Fig. 2, the tip of the nozzle of the molding machine or the pressure sensor arranged at the sprue portion closest to the nozzle tip of the mold, the pressure obtained from the temperature sensor, the temperature, and the injection speed attached to the injection molding machine. This is the part that measures the signal at every moment.

Reference numeral 2 denotes a molding machine characteristic calculation section for calculating the relationship between the injection speed and the time history of pressure from one molding machine characteristic measurement section. In No. 2, the injection speed and the resin temperature are kept constant and the holding pressure value is changed to obtain a pressure history as shown in FIG. By obtaining the pressure difference from the pressure at the nozzle tip and the injection pressure at the time of pressure holding from the obtained pressure history, the relationship between the pressure holding set value and the pressure loss of the molding machine can be obtained as shown in FIG. Next, in 2, the temperature of the molten resin is kept constant, the injection speed is changed, and a pressure history until completion of filling is obtained as shown in FIG. When the pressure loss of the molding machine shown in FIG. 4 corresponding to the pressure level is subtracted from the pressure history obtained as shown in FIG. 5, the relationship of the pressure history of the nozzle tip as shown in FIG. 6 is obtained.

3 is a molding condition, that is, an injection speed and a holding pressure set value. Reference numeral 4 is a portion for calculating the pressure history of the nozzle portion from filling to holding pressure based on the relationship shown in FIGS. 6 and 4 based on the molding conditions of 3.

Reference numeral 5 denotes an injection molding process simulation system for predicting the amount of filling, holding pressure, cooling, and warp deformation by the finite element method, finite volume method, difference method, boundary element method, or the like.

Reference numeral 6 is a molded product model including a sprue runner used in the simulation of the injection molding process 5. The pressure history of the nozzle tip calculated by 4 is given as the boundary condition of the resin inlet of the 6 model.

Reference numeral 7 is an analysis result of pressure, temperature time history, warp deformation amount, etc. of each part of the model obtained by 5.

[0016]

EFFECTS OF THE INVENTION Analysis conditions for performing injection molding process simulation must be given to the resin inflow port. However, since there is a large difference between the injection pressure and the nozzle tip pressure, it was difficult to give accurate conditions. Therefore,
A means for estimating a pressure history of a nozzle tip from a set value of an injection molding machine and calculating conditions for simulation of an injection molding process is provided.

[Brief description of drawings]

1 is a flow chart of an embodiment of the method of the present invention.

FIG. 2 is a diagram showing a configuration of an injection molding machine characteristic measuring unit.

FIG. 3 is a diagram showing an injection pressure and a pressure history of a nozzle tip obtained by using a holding pressure set value as a parameter.

FIG. 4 is a diagram showing a holding pressure set value and a pressure loss of the molding machine during the holding pressure. It can be seen that the pressure loss of the molding machine increases as the pressure increases.

FIG. 5 is a diagram showing a history of injection pressure until completion of filling, with injection speed as a parameter.

FIG. 6 is a diagram in which the pressure loss of the molding machine is removed from the injection pressure history.

FIG. 7 is an example of a molded product model including a sprue runner.

[Explanation of symbols]

a: Nozzle tip pressure b: Nozzle tip temperature c: injection speed d: Injection pressure e: Mold f: cavity g: Cylinder

Claims (3)

[Claims] 1. In an injection molding method, an injection pressure history and a pressure history near a resin inlet are measured as injection characteristics of a molding machine, and from the injection characteristic curve, a pressure loss amount corresponding to the pressure and a molding machine are measured.・ A method to calculate the pressure history at the nozzle tip by subtracting the pressure loss corresponding to the combination of cylinders. 2. A program for calculating a pressure history of a nozzle tip by the method according to claim 1. 3. A method for performing an injection molding process simulation, wherein the pressure history at the nozzle tip at the maximum temperature and the maximum cylinder speed obtained according to claim 1 is used as the pressure history at the resin inlet.