JP2017165028A - Plasticization simulation device, and plasticization simulation method and plasticization simulation program of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide plasticization simulation device and method capable of accurately calculating plasticization capability even with a double flight screw type plasticizer device as a target, and a program of the same.SOLUTION: A plasticization simulation device includes: an acquisition unit 101 which acquires a parameter including resin physical properties, an operation condition, and constitution data of the plasticization device having data of sub-flight, and initial plasticization capability; and an analysis unit 102 which calculates a physical amount including a melting amount based on the initial plasticization capability, the parameter, a mass conservation equation, and an energy conservation equation, calculates the melting amount using a first time increment in a first state where a solid bed height is within a cylinder height or a second time increment obtained by dividing the first time increment by a predetermined value in a second state where the solid bed height exceeds the cylinder height, calculates the maximum flow rate being the melting amount per unit time of a resin material based on the melting amount, and calculates plasticization capability using three-dimensional flow calculation based on the parameter, the physical amount, and the maximum flow rate.SELECTED DRAWING: Figure 3

Description

  Embodiments described herein relate generally to a plasticizing simulation apparatus that simulates a plasticizing process of a molding material, particularly a resin material, using a double flight screw type plasticizing apparatus, a plasticizing simulation method thereof, and a plasticizing simulation program.

  Conventionally, a simulation technique for simulating a plasticizing process by calculating physical quantities such as a resin temperature and a solid phase ratio of a resin material melt-plasticized in a plasticizer represented by an injection molding machine or an extruder is known. . Generally, in such a simulation, the plasticizing ability (kg / h) indicating the weight of the material plasticized per unit time is used for calculation of the physical quantity, and this plasticizing ability is fixed. Alternatively, it is widely practiced to calculate a physical quantity using plasticizing ability calculated using a predetermined screw characteristic equation (see Patent Documents 1 and 2 and Non-Patent Documents 1 and 2 below). On the other hand, these simulation techniques perform CAE (Computer Aided Engineering) analysis, specifically flow analysis, using resin physical properties, operating conditions, plasticizer specifications, etc. as input values. The shaft single flight screw type plasticizer is the object of analysis.

JP 2007-007951 A Japanese Patent Application No. 2015-124948

Nippon Steel Works Technical Report No. 63 Engineering Principles of Plasticizing Extraction

  In a double flight screw type (barrier flight screw type) plasticizing apparatus in which a subflight is provided on a screw, a set of resin materials (solid bed) in a solid state is forcibly deformed by the subflight. For this reason, it is difficult to accurately calculate the plasticizing ability of a double flight screw type plasticizer using a melting model and calculation flow used for flow analysis for a single flight screw type plasticizer. It was.

  The present invention has been made to solve the above-described problems, and a plasticization simulation apparatus and a plasticizer capable of accurately calculating the plasticizing ability even when a double-flight screw type plasticizing apparatus is targeted. An object of the present invention is to provide a simulation method and a plasticization simulation program.

  In order to solve the above-described problem, one aspect of the present invention is a three-zone model in which a resin material in a cylinder in a double flight screw type plasticizing apparatus is in a state of a solid bed, a melt film, or a melt pool. A plasticization simulation apparatus for calculating plasticizing capacity based on the parameters, including resin physical properties of the resin material, operating conditions of the plasticizing apparatus, and configuration data of the plasticizing apparatus having subflight configuration data; A physical quantity including a melting amount based on the information acquisition unit for acquiring the initial plasticizing capability, the initial plasticizing capability, the parameter, the mass conservation equation and the energy conservation equation, and the calculation of the melting amount In the first state in which the solid bed height is within the cylinder height, the solid bed height is determined using the first time increment. In the second state in which the cylinder height exceeds the physical amount calculation unit using a second time interval obtained by dividing the first time interval by a predetermined value, and the melting amount of the resin material per unit time based on the melting amount A maximum flow rate calculation unit that calculates a maximum flow rate, and a plasticization capability calculation unit that calculates a plasticization capability using a three-dimensional flow calculation based on the parameter, the physical quantity, and the maximum flow rate.

  Further, one aspect of the present invention has a plasticizing ability based on a three-zone model in which a resin material in a cylinder in a double flight screw type plasticizing apparatus is in a solid bed, a melt film, or a melt pool. A plasticization simulation method executed by the calculated plasticization simulation apparatus, the parameter including the resin physical properties of the resin material, the operating conditions of the plasticizer, and the configuration data of the plasticizer having subflight configuration data A physical quantity including a melting amount based on the initial plasticizing ability, the parameter, a mass conservation equation, and an energy conservation equation, and calculating the melting amount. In the first state where the solid bed height is within the cylinder height, the first time step is used to In the second state where the bed bed height exceeds the cylinder height, the step of using a second time step obtained by dividing the first time step by a predetermined value, and the melting per unit time of the resin material based on the melting amount Calculating a maximum flow rate that is a quantity, and calculating a plasticizing ability using a three-dimensional flow calculation based on the parameter, the physical quantity, and the maximum flow rate.

  Further, one aspect of the present invention has a plasticizing ability based on a three-zone model in which a resin material in a cylinder in a double flight screw type plasticizing apparatus is in a solid bed, a melt film, or a melt pool. A plasticization simulation program for causing a computer to execute calculation, the computer comprising: resin property of the resin material; operation conditions of the plasticizer; and configuration data of the plasticizer having subflight configuration data; And an information acquisition unit for acquiring an initial plasticizing capacity, an initial plasticizing capacity, the parameter, a mass conservation formula and an energy conservation formula, and calculating a physical quantity including a melting amount, In the calculation of the melting amount, in the first state where the solid bed height is within the cylinder height, In the second state in which the solid bed height exceeds the cylinder height using a one-hour increment, based on the physical quantity calculation unit using the second time increment obtained by dividing the first hour increment by a predetermined value, A maximum flow rate calculation unit that calculates a maximum flow rate that is a melting amount per unit time of the resin material, and a plasticity that calculates a plasticizing capability using a three-dimensional flow calculation based on the parameter, the physical quantity, and the maximum flow rate. It functions as an optimization ability calculation unit.

  According to the present invention, even when a double flight screw type plasticizing apparatus is targeted, the plasticizing ability can be calculated with high accuracy. The other effects of the present invention will be described in the section for carrying out the invention below.

It is a schematic sectional drawing which shows the single axis double flight screw type injection molding machine simulated in this Embodiment. It is a block diagram which shows the hardware constitutions of the plasticization simulation apparatus which concerns on this Embodiment. It is a functional block diagram which shows the function structure of the plasticization simulation apparatus which concerns on this Embodiment. It is a figure for demonstrating a 3 zone model. It is a figure for demonstrating the flow restriction | limiting in a 3 zone model. (A) is a figure which shows the unfolded model of a single flight type screw, (b) is a double flight type screw. (A) is the sectional view on the AA line in FIG.6 (b), (b) is the sectional view on the BB line in the same figure. It is a flowchart which shows the plasticization analysis process which concerns on this Embodiment. It is a flowchart which shows an initial plasticization capability calculation process. It is a flowchart which shows a flow analysis process. It is a flowchart which shows a physical quantity calculation process. It is a flowchart which shows a fusion amount calculation process. It is a flowchart which shows a fusion | melting amount division | segmentation process. It is a flowchart which shows a plasticization capability calculation process. (A) is the steady-state plasticizing ability calculated by the plasticization analysis process, (b) is the steady-state plasticizing ability derived from the experimental results of the actual machine, and (c) shows the error of these results. FIG. It is a figure which shows the case where a plasticization simulation program is applied to information processing apparatus.

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

  In the present embodiment, as shown in FIG. 1, a cylinder 1 for melting a resin material, a hopper 2 provided on the upstream side of the cylinder 1 and charged with the resin material, and rotatable in the cylinder 1. The resin material is plasticized by calculating various physical quantities in a steady state of an injection molding machine 4 provided with a single screw 3 that melts and kneads the resin material and conveys it to the tip (downstream side) of the cylinder 1. A plasticization simulation apparatus that enables simulation in the plasticizing process will be described as an example. In the screw 3 of the injection molding machine 4, two main flights 32 are spirally provided with a predetermined distance from the peripheral surface of the screw shaft 31, and the screw 3 is interposed between the main flights 32. This is a so-called double flight screw in which a subflight 33 having a length in the radially outward direction shorter than that of the main flight 32 is spirally provided. That is, the injection molding machine 4 according to the present embodiment is configured as a single-shaft double flight screw type injection molding machine.

  In the present embodiment, an explanation will be given by taking an injection molding machine as an example of a plasticizing apparatus to be simulated, but the present invention is not limited to this. The present invention can also be applied to other plasticizing apparatuses. Hereinafter, the details of the present embodiment will be described with reference to the drawings.

(Device configuration)
FIG. 2 is a block diagram showing a hardware configuration of the plasticization simulation apparatus according to the present embodiment. As shown in FIG. 2, the plasticization simulation apparatus 10 includes a CPU (Central Processing Unit) 11, a storage unit 12, an input unit 13, a display unit 14, and an HDD (Hard disk drive) 15.

  The CPU 11 executes various programs such as an OS (Operating System), a BIOS (Basic Input / Output System), and an application developed on the storage unit 12 to control the plasticization simulation apparatus 10. The storage unit 12 is a volatile memory such as a so-called RAM (Random Access Memory), and is used as a work area for a program to be executed.

  The input unit 13 receives an input (for example, various parameters described later) from a user who uses the plasticization simulation apparatus 10, and for example, a mouse that is a pointing device for designating a specific position on the display, A keyboard in which a plurality of keys to which characters or specific functions are assigned are arranged.

  The display unit 14 is an output device such as an OS and a GUI (Graphical User Interface) of an application operating on the OS and a display for displaying an analysis result. With such an output device, for example, the physical quantity calculated as the analysis result is displayed in the form of a histogram. The HDD 15 is a so-called non-volatile storage area in which data such as various parameters used in plasticization analysis processing described later and physical quantities calculated by the processing are stored.

(Functional configuration)
Next, the functional configuration of the plasticization simulation apparatus 10 will be described. FIG. 3 is a functional block diagram showing a functional configuration of the plasticization simulation apparatus according to the present embodiment. As illustrated in FIG. 3, the plasticization simulation apparatus 10 includes an acquisition unit 101, an analysis unit 102, a determination unit 103, and an output unit 104 as functions. These functions are realized by the cooperation of the above-described hardware resources such as the CPU 11 and the storage unit 12, and the plasticization analysis process described later is performed by these functions.

  The acquisition unit 101 acquires various parameters necessary for calculating a predetermined physical quantity. As the parameter, information manually input by the user may be acquired, or information uniquely associated with the injection molding machine 4 to be analyzed may be acquired from the HDD 15. The analysis unit 102 calculates plasticizing ability and various physical quantities as analysis values of simulation based on the acquired various parameters. The determination unit 103 performs various determinations in the plasticization analysis processing. The output unit 104 receives the calculation result of the analysis unit 102 and the determination result of the determination unit 103, and sends these results to the display unit 14 and the HDD 15. Output.

(Overview)
In order to facilitate understanding, an outline of plasticization analysis processing according to the present embodiment will be briefly described. FIG. 4 is a diagram for explaining the three-zone model, and shows the state of the resin material in the groove of the screw 3. FIG. 5 is a diagram for explaining the flow restriction in the three-zone model. In the plasticization analysis process performed by the plasticization simulation apparatus 10 according to the present embodiment, various physical quantities such as a molten resin amount (also referred to as a melt amount as appropriate), a resin temperature, a solid phase ratio, a melt film thickness, screw power, pressure, and the like. Following the Tadmor model, the three-zone model as shown in FIG. 4 is introduced and divided into zones as appropriate. Reference numeral 51 shown in FIG. 4 indicates a solid bed in which the resin material exists in a solid region in the region including the screw 3 and the main flight 32 of the screw 3, and reference numeral 52 indicates a melt film that promotes melting of the resin material. Reference numeral 53 indicates a melt pool in which a molten resin that is a resin material in a molten state stays.

  The resin material to be plasticized in the three-zone model flows with a flow velocity vector indicated by each arrow as shown in FIG. Since the resin material is pushed out by the screw 3, the flow velocity vector is also given to the cylinder 1 here. Originally, the molten resin in the melt film 52 is brought into contact with the cylinder 1 so that its melting is promoted, but the flow rate of the molten resin flowing into the melt pool 53, in other words, at the boundary between the melt film 52 and the melt pool 53. The flow rate of a certain mesh does not exceed the melting amount of the molten resin (melting amount of the solid bed 51) of the melt film 52 of the mesh. Therefore, in the plasticization analysis processing in the present embodiment, the flow rate of the flow velocity vector 60 flowing from the melt film 52 to the melt pool 53 out of the molten resin flow velocity vector is limited so as not to exceed the melt amount of the melt film 52. The flow restriction is incorporated into the calculation of plasticizing ability.

  In addition, the plasticization analysis processing according to the present embodiment using such a three-zone model incorporates processing that takes into account the acceleration of melting of the resin material due to the formation of the subflight 33, that is, the increase in plasticizing ability. It is. The concept of increasing the plasticizing ability will be briefly described with reference to FIGS. FIG. 6A is a view showing a developed model of a single flight type screw, and FIG. 6B is a view showing a developed model of a double flight type screw. 7A is a cross-sectional view taken along line AA in FIG. 6B, and FIG. 7B is a cross-sectional view taken along line BB in FIG. Δ shown in FIG. 7 indicates the thickness of the melt film 52, and C indicates the radially outward direction of the screw 3.

  In the case of a single flight screw, as shown in FIG. 6A, the solid bed 51 is located so as to be biased toward the main flight 32 on one side and can move freely. On the other hand, in the case of a double flight screw, the solid bed 51 is blocked by the subflight 33 as shown in FIG. 6 (b), and its movement is restricted. Therefore, the solid bed 51 is forcedly deformed by the subflight 33, and the deformation becomes larger as the subflight 33 is narrowed downstream.

  That is, as shown in FIG. 7A, the upstream solid bed 51 has its interface with the melt film 52 still located near the upper end of the subflight 33, whereas the downstream solid bed 51 Therefore, the subflight 33 is deformed so as to extend along the radially outward direction C. From this, the thickness δ of the melt film 52 becomes thinner in accordance with the deformation of the solid bed 51. This decrease in the thickness δ of the melt film 52 leads to an increase in the melt amount of the melt film 52 per unit time. In the present embodiment, since the flow rate is limited according to the melting amount, the increase in the melting amount leads to an increase in the upper limit value of the flow rate limitation. Therefore, compared with a single flight type screw, the double flight type screw 3 has an increased plasticizing ability.

  Here, the principle that the decrease in the thickness δ of the melt film 52 leads to the increase in the melt amount per unit time will be briefly described. The shear heating value (shear energy) applied to the resin material in the plasticizing step is represented by the following formula (1), and the shear rate is represented by the following formula (2).

In the formulas (1) and (2), Q is a shear heating value, η is a resin viscosity, γ ^{· is a} shear rate, δ is a melt film thickness, and V is a screw speed. As can be seen from the equations (1) and (2), when the melt film thickness δ decreases, the shear rate γ ^· increases, and the shear heating value Q increases accordingly.

  The temperature rise amount of the melt film 52 is represented by the following formula (3), and the melt film temperature is represented by the following formula (4).

In the formulas (3) and (4), ΔT is the amount of temperature rise of the melt film, ρ is the density of the melt film, C is the specific heat of the melt film, Q is the amount of heat generated by shearing, and T _{f is the} melt film temperature. . As can be seen from the equations (3) and (4), the increase in the shear heating value Q increases the melt film temperature _Tf .

  The heat flux from the center of the melt film 52 to the interface of the solid bed 51 is represented by the following equation (5), and the melting amount is represented by the following equation (6).

In this equation (5), q: heat flux from the melt film center to the solid bed surface ^{([W / m 2])} , k m: thermal conductivity of the melt (melt film), [delta]: melt film thickness, T _f : Melt film temperature, T _m : Resin melting point, Q: Shear heating value, ΔV: Melting amount, ρ: Melt film density, H: Heat of fusion (enthalpy), q ′: Heat flux to solid bed, dt : Time step. As can be seen from the equation (5), the heat flux q increases as the melt film temperature _Tf increases and the melt film thickness δ decreases. Further, as can be seen from the equation (6), the amount of melting per unit time (time increment: dt) increases as the heat flux q increases. From the above, a decrease in the thickness of the melt film 52 leads to an increase in the melt amount per unit time.

(Processing operation)
Hereinafter, the details of the operation of the plasticization simulation apparatus 10 according to the present embodiment will be described with reference to the drawings. FIG. 8 is a flowchart showing plasticization analysis processing according to the present embodiment. Each value calculated in this process is appropriately stored in the storage unit 12 or the HDD 15 by the output unit 104. Therefore, the storage process of each value is omitted in this flow. As shown in FIG. 8, the plasticization analysis processing according to the present embodiment first has an initial plasticizing capability that is a plasticizing capability of an initial value used in processing such as calculation of physical quantity and calculation of shear rate distribution. An initial plasticizing ability calculation process for calculation is executed (S1). Thereafter, an analysis process for calculating each physical quantity as an analysis result is executed (S2), and this flow ends. Hereinafter, details of each of these processes will be sequentially described.

  First, details of the initial plasticizing ability calculation process will be described. FIG. 9 is a flowchart showing the initial plasticizing ability calculation process. As shown in FIG. 9, first, the acquisition unit 101 acquires various parameters of resin physical properties, operating conditions, and configuration data of the injection molding machine 4 for calculating plasticizing ability and physical quantities (S101, S102, S103). Examples of the resin physical property parameters acquired in step S101 include model parameters by viscosity fitting, solid and melt density, specific heat, thermal conductivity, melting point, and heat of fusion. The operating condition parameters acquired in step S102 include, for example, screw rotation speed, screw tip pressure, cylinder set temperature, cylinder set temperature boundary position, screw position, number of mesh steps, number of calculation cycles, amount of metered resin, raw material resin Examples include temperature and back pressure. As parameters of the configuration data acquired in step S103, for example, cylinder diameter, screw diameter, screw groove depth, screw lead, main flight width, main flight clearance, subflight start position, subflight end position, subflight clearance Etc. This configuration data is preferably each value in a plurality of calculation regions (each position of the screw 3) such as the tip portion of the screw 3 and the supply portion near the hopper 2.

  Based on the acquired parameters, the analysis unit 102 calculates the initial plasticizing ability (S104), and this flow ends. The initial plasticizing ability calculated here is indicated by the weight [kg / h] of the resin material (molten resin) per unit time, and is represented by the following screw characteristic formula (7) or (8). Is calculated using In addition, (7) Formula is used for the calculation in the traction flow part which is the part to which the resin material is pulled by the screw 3 in the cylinder 1, and (8) Formula is used for the calculation in another part.

In the equations (7) and (8), Q: volume flow rate, A and B: coefficient, V _bz : moving speed in the resin flow direction, w: screw groove width, h: screw groove depth, φ: Screw helix angle, η: resin viscosity, ∂P / ∂z: pressure change amount. Further, the resin viscosity η in the equation (8) can be obtained from the following viscosity equations (9) and (10).

In the equations (9) and (10), η: resin viscosity, A, a, b, c: viscosity coefficient, g: shear rate, _Tr and n: viscosity parameter, and T: resin temperature. By introducing necessary parameters among various parameters acquired by the acquisition unit 101 into these equations (7) to (10), the initial plasticizing ability is calculated. Necessary parameters here are screw rotation speed, cylinder diameter, screw groove depth, melt density, and the like.

  Next, details of the analysis processing will be described. FIG. 10 is a flowchart showing the analysis process. As shown in FIG. 10, first, the analysis unit 102 acquires the various parameters acquired by the acquisition unit 101 and the calculated initial plasticizing capability from the storage unit 12 or the HDD 15 (S201), and acquires the acquired initial plasticizing capability. Is set as the first plasticizing ability (S202). After the setting, a physical quantity calculation process is executed based on these data (S203). The physical quantity calculation process is a process of calculating the maximum flow rate of the molten resin from the melt film 52 in order to perform the flow rate restriction described above together with the physical quantities such as the solid phase ratio and the melt film thickness, and details thereof will be described later.

  After the physical quantity calculation processing, the analysis unit 102 creates a shape mesh of the melt pool 53 from the calculated solid phase rate and the melt film thickness (S204). The method for creating the shape mesh may be a lattice mesh using a method such as a finite volume method, for example, and is a general method and will not be described here. After creating the shape mesh, the analysis unit 102 executes a plasticizing ability calculation process (S205). The plasticizing ability calculation processing is processing for calculating the outflow amount of the molten resin from the melt film 52 to the melt pool 53 using the three-dimensional flow calculation, and setting this as the second plasticizing ability. Details of this plasticizing ability calculation processing will be described later.

  After calculating the second plasticizing ability, the determination unit 103 determines whether or not the calculated second plasticizing ability satisfies a predetermined condition (S206). In the present embodiment, the predetermined condition is that the amount of change between the first plasticizing ability and the second plasticizing ability is 0.01% or less. This is a process performed because the position where the melt pool 53 is generated differs depending on the plasticizing ability, and it can be determined that the steady state is reached when the amount of change is extremely small. Note that the amount of change is not limited to this value, and may be any value that can be determined that there is no change in plasticizing ability, and may be, for example, 0.1 or 0.005. Therefore, a smaller value is preferable.

  When it is determined that the second plasticizing ability does not satisfy the predetermined condition (S206, NO), the analysis unit 102 updates the second plasticizing ability as the first plasticizing ability and obtains a new first plasticizing ability. (S207), the process proceeds to the physical quantity calculation process of step S203. On the other hand, when it is determined that the second plasticizing ability satisfies the predetermined condition (S206, YES), the analysis unit 102 performs the same process as the physical quantity calculating process in step S203 based on the second plasticizing ability. By doing so, each physical quantity is calculated (S208). After the calculation, the output unit 104 appropriately outputs the second plasticizing capability and each physical quantity based on the second plasticizing capability to the storage unit 12, the display unit 14, and the HDD 15 according to the user's input (S209), and this flow ends. . For example, the output unit 104 outputs each physical quantity to an output file designated in advance for each calculation region (position) on the screw 3 and displays it on the display unit 14.

  Next, details of the physical quantity calculation processing will be described. FIG. 11 is a flowchart showing physical quantity calculation processing. According to the Tadmor model, the physical quantity calculation processing according to the present embodiment calculates physical quantities such as a solid phase ratio, melt film thickness, and melt amount, and calculates a shear rate calculation of the melt film 52 by two-dimensional flow calculation. The maximum flow rate of the melt film 52 is calculated based on The calculation accuracy and the calculation speed are improved by obtaining the shear rate by two-dimensional flow calculation. D shown in FIG. 11 indicates a processing part of the two-dimensional flow calculation.

  As shown in FIG. 11, first, the analysis unit 102 acquires various parameters and first plasticizing capability acquired by the acquisition unit 101 from the storage unit 12 or the HDD 15 (S301), and based on these, various physical quantities are obtained. Calculate (S302). In the present embodiment, the physical quantity is appropriately calculated based on the Tadmor model. However, the melting amount is calculated by separately using the Tadmor model and its improved model in the melting amount calculation process described later. Examples of the physical quantity calculated here include resin temperature, solid phase ratio, melt film thickness, screw power, pressure, solid bed width (length in the main flight width direction), and solid bed volume. These physical quantities are calculated over the entire calculation region (for each mesh), but the resin temperature and the solid phase ratio are calculated separately for each of the solid bed 51, the melt film 52, and the melt pool 53. These physical quantities are described later for the melt film 52 by using the first plasticizing ability, the necessary parameters among the parameters acquired by the acquisition unit 101, the law of conservation of mass and the law of conservation of energy. Calculated separately using the divided shear heating value. Specifically, the following formulas (11) and (12) are used to calculate various physical quantities in the solid bed 51.

In the equations (11) and (12), ρ: resin density, X: solid bed width, h: screw groove depth, δ _m : melt film thickness, H: enthalpy, v _sz : flow direction of the solid bed Movement speed, λ: heat of melting, m ^· _f : melt flow rate on the melt film side of the solid bed, m ^· _p : melt flow rate on the melt pool side of the solid bed, k _s : thermal conductivity of the solid resin, T _s : solid Bed temperature, q _fs : heat flux from the melt film to the solid bed interface, q _ps : heat flux from the melt pool to the solid bed interface.

  Further, the following formulas (13) and (14) are used to calculate the physical quantities in the melt film 52.

In the equations (13) and (14), ρ: resin density, X: solid bed width, δ _m : melt film thickness, H: enthalpy, v _fz : melt film flow direction speed, v _fx : melt film scraping direction _{velocity, q fs:} heat flux from the melt film to the internal solid bed, _{k m:} melt thermal conductivity, _{T f:} melt film _{temperature, q Bf:} heat flux from the cylinder to melt the film, _{Q G:} melt film M ^· _f : Melt mass flow rate on the melt film side of the solid bed. Note that the Q _G is introduced split shear heating value to be described later.

  Further, the following formulas (15) and (16) are used to calculate the physical quantities in the melt pool 53.

In the equations (15) and (16), ρ: resin density, w: screw groove width, X: solid bed width, h: screw groove depth, H: enthalpy, v _pz : velocity in the melt pool flow direction, [delta] _m: melt film _{thickness, q ps:} heat flux from the melt pool to the solid bed surface, _{k m:} melt thermal conductivity, _{T p:} melt pool _{temperature, v fx:} melt film scraping direction _{velocity, q Bp:} cylinder From the heat flux to the melt pool, Q ′ _G : Melt pool shear heating value, m _p : Melt pool side melt mass flow rate of the solid bed.

  The above-described equations (11), (13), and (15) represent the energy conservation laws, and the equations (12), (14), and (16) represent the mass conservation laws. Further, since the mass conservation law and the energy conservation law are divided into the solid bed 51, the melt film 52, and the melt pool 53, a melting mass flow rate is introduced so as to satisfy the mass conservation law and the energy conservation law. By appropriately introducing necessary parameters among the acquired parameters, the first plasticizing ability, the divided shear heating value, etc. into these mathematical expressions, the resin temperature, solid phase ratio, melt film thickness, screw power, pressure Etc. can be calculated.

  The shear heating value in the melt film 52 is calculated based on the resin temperature and the melt film thickness calculated as physical quantities. Therefore, in the processing for calculating various physical quantities in step S302 in the present embodiment, as shown in FIG. 11, first, the resin temperature and the melt film thickness are calculated (S3021), and the melt film 52 is calculated by two-dimensional flow calculation based on these. After calculating the velocity distribution and shear rate distribution inside (S3022, S3023), and calculating the resin viscosity and shear heating value in the melt film 52 (S3024), other physical quantities are calculated (S3025).

  Here, the processing from step S3022 to step S3025 in the present embodiment will be described. First, the analysis unit 102 performs general two-dimensional flow calculation based on the acquired parameters (such as screw rotation speed) and the calculated resin temperature and melt film thickness, and the velocity distribution of the molten resin in the melt film 52 is calculated. Is calculated (S3022). After the calculation, the analysis unit 102 calculates the shear rate for each mesh in the melt film 52 represented by the following equation (17) based on the speed distribution, and calculates the shear rate distribution in the melt film 52 (S3023). ).

In the equation (17), γ ^· : shear rate, du: mesh speed difference, dy: 1 mesh distance (thickness).

  After the calculation of the shear rate distribution, the resin viscosity and the shear heating value for each mesh in the melt film 52 are calculated based on the shear rate distribution (S3024). The resin viscosity may be obtained by a general method of two-dimensional analysis, or may be obtained by the viscosity formulas of the above formulas (9) and (10). The shear heating value can be obtained by the above equation (1). After calculating the resin viscosity and the shear heating value, the remaining physical quantities, that is, the physical quantities other than the resin temperature and the melt film thickness are calculated using the above-described equations (11) to (16) as appropriate (S3025).

In each of the above equations, the heat flux q _fs from the melt film 52 to the solid bed 51 interface is represented by the following equation (18), and the heat flux q _ss from the solid bed interface to the solid bed 51 is represented by the following equation (19). Can be sought.

(18) In the formula and _{(19), q fs:} heat flux from the melt film to the solid bed ^{([W / m 2])} , k m: thermal conductivity of the melt, _{T f:} Melt film temperature, T _m : resin melting point, δ: melt film thickness, Q: shear heating value, q _ss : heat flux into solid bed ([W / m ² ]), k _s : solid thermal conductivity, h: screw groove Depth, A: parameter, B: parameter, C: parameter.

Here, in the present embodiment, C / (A + B + C) of the shear heating value in the melt film 52 is used for the temperature increase in the melt film 52. That is, among the plurality of meshes, for the mesh corresponding to the melt film 52, the shear heating value obtained by the above equation (1) is multiplied by C / (A + B + C), and this C / (A + B + C) is calculated in each physical quantity calculation described above. ) Is used. Hereinafter, the shear heating value divided into A / (A + B + C), B / (A + B + C), and C / (A + B + C) in the melt film 52 is referred to as a divided shear heating value. For example, the Q _G in the above (13), dividing the shear heat generation amount is introduced. The reason why the shear heating value is C / (A + B + C) is as follows.

  The heat flux from the center of the melt film 52 to the interface of the solid bed 51 is obtained by the above equation (18). According to this, it can be seen that the shear heating value A / (A + B + C) flows to the solid bed 51. Further, the heat flux from the cylinder 1 to the melt film 52 is obtained by the following equation (20). According to this, it can be seen that B / (A + B + C) flows into the cylinder 1 as the shear heating value. Therefore, it can be seen that the remaining C / (A + B + C) shear heating value remains in the melt film 52 and is used to increase the temperature of the molten resin. Therefore, by dividing the shear heating value of the mesh corresponding to the melt film 52 into A / (A + B + C), B / (A + B + C), and C / (A + B + C), it is possible to give a heat amount in accordance with the reality. By using the plasticizing ability and calculation of each physical quantity, a highly accurate analysis result can be obtained.

In this formula _{(20), q bf:} heat flux from the cylinder to melt the film, _{k m:} thermal conductivity of the melt, _{T b:} the cylinder temperature, _{T f:} Melt film temperature, [delta]: Melt film thickness, Q : Shear heat value, A: parameter, B: parameter, C: parameter.

After the physical quantity is calculated as described above, a melt amount calculation process for calculating the melt amount of the molten resin in the melt film 52 is executed (S303), and the analysis unit 102 uses the calculated melt amount as a unit time (time increment: dt). The maximum flow rate per unit time ([m ³ / s]) of the molten resin flowing from the melt film 52 to the melt pool 53 is calculated (S304), and this flow ends.

  Next, details of the above-described melting amount calculation processing will be described. FIG. 12 is a flowchart showing the melting amount calculation process. As shown in FIG. 12, first, the analysis unit 102 selects a mesh (including three zones as shown in FIG. 7) to be a calculation region (S401), and acquires the main flight width and subflight acquired as parameters. Based on the start position and the subflight end position, the subflight width in the selected mesh is calculated (S402). The subflight width here means the width from the main flight 32 on the solid bed 51 side. After calculating the subflight width, the determination unit 103 determines whether the solid bed width (calculated as a physical quantity) corresponding to the selected mesh is equal to or smaller than the subflight width (S403). When the solid bed width is equal to or smaller than the subflight width (S403, YES), the melt film 52 is obtained by solving the following equation (21) using the shear heating value (divided shear heating value) calculated as a physical quantity and the heat flux. The melted amount of the molten resin is calculated (S404).

In the equation (21), ΔV: melting amount ([m ³ ]), q _fs : heat flux from the melt film to the solid bed, q _ss : heat flux into the solid bed, W _s : solid bed width, dz: flow direction mesh width, ρ: resin density, C _p : resin specific heat, T _m : resin melting point, T _s : solid bed temperature, H: resin melting heat. The maximum flow rate m can be calculated by dividing the melt amount ΔV by the time increment dt. Therefore, the amount of melting can also be expressed as mdt.

  After calculating the melting amount, the determination unit 103 determines whether or not all meshes have been selected (S406). If all meshes have been selected (S406, YES), this flow ends and all meshes have been selected. If not (S406, NO), the analysis unit 102 selects the next mesh as the calculation target of the melting amount (S407), and proceeds to the calculation of the subflight width in S404 again. On the other hand, when the solid bed width is not less than or equal to the subflight width (S403, NO), the melting amount dividing process is performed (S405), and the process proceeds to the process of determining whether all the meshes in step S406 have been selected. Below, the detail is demonstrated about a fusion | melting amount division | segmentation process.

  In the melting amount division process, a calculation contradiction due to the formation of the subflight 33, specifically, the solid bed 51 is forcibly narrowed by the subflight 33, thereby reducing the height of the solid bed (FIG. 7). This is a process for avoiding a contradiction in calculation that the length of the screw 3 in the radial direction C shown in FIG. 2 exceeds the cylinder height (height from the peripheral surface of the screw shaft 31 to the cylinder 1). . In the present embodiment, the time increment is finely set according to predetermined conditions, and the virtual mesh subdivision is reproduced to finely change the melting amount, thereby avoiding this contradiction and improving the calculation speed. Is realized.

  FIG. 13 is a flowchart showing the melt amount dividing process. As shown in FIG. 13, first, the analysis unit 102 calculates the solid bed height (S501). At present, since the solid bed 51 is in contact with the subflight 33, the solid bed height can be calculated by replacing the solid bed width with the subflight width, for example, and calculating the solid bed density and the three-axis direction of the screw. It can be calculated by keeping the length (mesh thickness) constant.

  After calculating the solid bed height, the determination unit 103 determines whether or not the solid bed height is equal to or less than the cylinder height (S502), and if the solid bed height is equal to or less than the cylinder height (S502, YES). The solid bed 51 is forcibly narrowed by the subflight 33, but it is determined that the solid bed height has not yet exceeded the cylinder height, and the melting amount is calculated in the same manner as in step S404 (S503). This flow ends. The cylinder height here may be given in advance, or may be calculated from the screw groove depth and the main flight clearance included in the acquired parameters.

On the other hand, when the solid bed height is not equal to or less than the cylinder height (NO in S502), the solid bed 51 is forcibly narrowed by the subflight 33, and it is determined that the solid bed height exceeds the cylinder height. Sets the time increment dt used to calculate the melting amount to ndt _new (S504), and again calculates the height of the solid bed (S505). The dt _new set here is preferably obtained by dividing dt, that is, by dividing dt by a predetermined value. For example, dt / 10. Here, n = 1. The solid bed height is calculated by the same calculation method as in step S501, but the subflight width needs to be calculated according to ndt _new . Although the method of calculating the subflight width is appropriate, for example, a displacement amount of the subflight width between the meshes is calculated, and a method of calculating by adding ndt _new / dt of the displacement amount to the subflight width of the immediately preceding mesh. There is.

After calculating the solid bed height, the determination unit 103 determines whether the solid bed height is equal to or less than the cylinder height (S506). If the solid bed height is not equal to or less than the cylinder height (S506, NO), In order to further divide the time interval ndt _{new, it} is divided by a predetermined value to obtain ndt _new / x (S507), further n = 1 (S508), and the process proceeds to the calculation of the solid bed height in step S506 again. The value of x here is, for example, 10 or the like.

On the other hand, when the solid bed height is equal to or less than the cylinder height (S506, YES), the melt amount is calculated in the same manner as in steps S404 and S503 (S509), and the total of ndt _new is dt _original (in steps S404 and S503). It is determined whether or not it is equal to or greater than the initial time step value used (S510). The sum of _{ndt new new} here, means a total of _{ndt new new} in a state that does not transition to the process of the _{ndt new = ndt} new / x in step S507, the thus, every time the transition to step S507, the This sum is initialized to zero. If the total of ndt _new is not greater than or equal to dt _original (S510, NO), 1 is added to n (S511), the amount of melting calculated from the solid bed volume of the target mesh is subtracted (S512), and the solid of step S506 is again obtained. Move on to bed height calculation. On the other hand, if the total of ndt _new is equal to or greater than dt _original (S510, YES), the melting amounts calculated for each ndt _new are added together (S513), and this flow ends.

According to the processing of step S510 to step S513, while the state where the solid bed height is equal to or less than the cylinder height is maintained, 1 is added to n, and the melt amount is continuously calculated, that is, a multiple of ndt _new . By calculating the melting amount every time, the melting amount can be calculated individually assuming that the subflight width is gradually narrowed, so that the time increment dt _new has reached the original time increment dt By adding the respective melting amounts, a highly accurate melting amount value can be obtained.

  Next, details of the plasticizing ability calculation process described above will be described. The plasticizing capacity calculation process according to the present embodiment is obtained by incorporating the flow restriction according to the present embodiment into a general incompressible flow calculation. FIG. 14 is a flowchart showing the plasticizing ability calculation process. As shown in FIG. 14, first, the analysis unit 102 generalizes the flow calculation, based on the following equations (22) and (23), which are basic equations of conservation laws, and calculates a temporary speed (melt film 52 The flow rate of the molten resin flowing from the water to the melt pool 53 is calculated (S601). After the calculation, the analysis unit 102 performs pressure correction of the calculated temporary speed and calculates the resin temperature based on the following equation (24) (S602). Here, the provisional speed whose pressure has been corrected will be referred to as a corrected speed and will be described below.

In the equation (22), from the left, one item is an unsteady term, two items are convection terms, three items are diffusion terms, and four items are generation terms. In the equations (23) and (24), ρ: density, C _p : specific heat, T: temperature, t: time, q: heat flux, τ: stress, v: velocity, P: pressure.

  After the pressure correction, the determination unit 103 determines whether it is necessary to limit the flow rate (S603). In the present embodiment, this determination is made with the correction speed at the mesh at the boundary between the melt film 52 and the melt pool 53 exceeding the maximum speed (maximum flow velocity) calculated based on the maximum flow rate calculated in the physical quantity calculation processing. Judgment is made based on whether or not. If the correction speed exceeds the maximum speed, it is determined that the amount of outflow flowing from the melt film 52 to the melt pool 53 is larger than the melt amount of the melt film 52, and it is determined that the flow rate needs to be restricted. The More specifically, the determination unit 103 calculates the maximum speed from the maximum flow rate using the following equation (25), and determines whether or not the maximum speed <the correction speed.

In the equation (25), v _max is the maximum speed, m is the maximum flow rate, δ is the melt film thickness, and Δz is the length of the three-dimensional mesh.

  When it is determined that it is necessary to limit the flow rate (S603, YES), the analysis unit 102 sets the correction speed to the maximum speed (S604), and performs a convergence process (mass mask) using the above formulas (23) and (24). The true speed is calculated by executing (balance) (S605). After the calculation, the analysis unit 102 calculates the volume of the mesh at the boundary between the melt film 52 and the melt pool 53 based on the true speed, and multiplies the volume by the density of the melt (molten resin) to obtain the second plasticizing capability. Is calculated (S606), and this flow ends. On the other hand, if it is determined that there is no need to limit the flow rate (S603, NO), the process proceeds to the process of calculating the true speed (S605) while leaving the correction speed as it is.

  The reliability of the analysis result calculated by the plasticization analysis process described above will be briefly described with reference to the drawings. FIG. 15A is a steady-state plasticizing ability calculated by the plasticization analysis process, FIG. 15B is a steady-state plasticizing ability derived from an experimental result in an actual machine, and FIG. 15C is an error of these results. FIG. The target resin of these experiments and simulations is PP (polypropylene), the unit of plasticizing ability is [kg / h], and the unit of error is [%]. Screw A and screw B are both double-flight type plasticizing devices in which subflights 33 are formed. Screw A is “M3D screw” manufactured by Nippon Steel Works, Ltd., and screw B is also manufactured by Nippon Steel Works, Ltd. It is a “test screw”.

  As shown in FIG. 15C, the calculation result and the experimental result had an error of about 10%. Therefore, according to the plasticization analysis processing according to the present embodiment, it can be seen that the plasticizing ability can be calculated with very high accuracy.

  According to the present embodiment, the plasticizing ability can be calculated with high accuracy from a three-dimensional flow calculation reflecting various conditions. In particular, according to the melting amount dividing process, even if the solid bed height virtually exceeds the cylinder height, the solid bed height does not exceed the cylinder height by dividing the time step. The amount of melting performed can be calculated, and the amount of melting with high accuracy can be calculated. Further, by incorporating a flow restriction based on this, the flow rate of the mesh at the boundary between the melt film 52 and the melt pool 53 can be restricted so as to be equal to or less than the maximum flow rate. It is possible to prevent an event that cannot actually occur such as exceeding. Therefore, it is possible to obtain a plasticizing ability with higher accuracy that is close to reality, and thus, it is possible to obtain a highly accurate analysis result. Furthermore, by calculating the plasticizing ability and each physical quantity based on the divided shear heating value, the shear heating value used for increasing the temperature of the molten resin in the melt film 52 can be set to an appropriate value, and the above effect Can be further increased. This is particularly noticeable in screw power. Further, since the shear rate distribution is calculated by two-dimensional flow calculation and this is reflected in the calculation of the physical quantity, it is possible to improve the calculation speed as well as the calculation accuracy.

  In the present embodiment, the initial plasticizing ability is calculated using the screw characteristic formula. However, assuming the plasticizing ability, an input or stored predetermined value is used as the initial plasticizing ability. You may make it acquire. Further, in the physical quantity calculation process, another physical quantity calculation process in step S3025 may be performed before the two-dimensional flow calculation.

  The present invention can be implemented in various other forms without departing from the gist or main features thereof. Therefore, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is shown by the scope of claims, and is not restricted by the text of the specification. Moreover, all modifications, various improvements, substitutions and modifications belonging to the equivalent scope of the claims are all within the scope of the present invention.

  Further, the various steps in the plasticization simulation apparatus 10 described in the embodiment are stored in a computer-readable portable recording medium 8 as shown in FIG. 16 as a plasticization simulation program, and the recording is performed. By causing the information processing apparatus 9 to read the medium 8, the information processing apparatus 9 can realize the above-described functions. As the recording medium 8, for example, an optical disk (CD-ROM, DVD disk, etc.), a magnetic disk (hard disk drive, etc.), a flash memory, an IC card, and a medium that can be transmitted via a network are read and executed by a computer. All possible media are included.

  The plasticization simulation apparatus described in the claims is, for example, the plasticization simulation apparatus 10 in the above-described embodiment. The information acquisition unit is, for example, the acquisition unit 101, and the physical quantity calculation unit, the maximum flow rate calculation unit, the height calculation unit, and the plasticizing ability calculation unit are, for example, the analysis unit 102. The width determination unit and the state determination unit are, for example, the determination unit 103.

  DESCRIPTION OF SYMBOLS 1 cylinder, 3 screw, 4 injection molding machine, 10 plasticization simulation apparatus, 33 subflight, 51 solid bed, 52 melt film, 53 melt pool, 101 acquisition part, 102 analysis part, 103 determination part.

Claims (5)

A plasticization simulation apparatus for calculating plasticizing ability based on a three-zone model in which a resin material in a cylinder in a double flight screw type plasticizing apparatus is in a solid bed, a melt film, or a melt pool. ,
Parameters including the resin physical properties of the resin material, the operating conditions of the plasticizing device, and the configuration data of the plasticizing device having the configuration data of subflights, and an information acquisition unit for acquiring initial plasticizing capability;
Based on the initial plasticizing capacity, the parameter, the mass conservation formula and the energy conservation formula, the physical quantity including the melting amount is calculated, and the solid bed height is within the cylinder height in the calculation of the melting amount. In the first state, using a first time step, in the second state where the solid bed height exceeds the cylinder height, a physical quantity calculation unit using a second time step obtained by dividing the first time step by a predetermined value;
A maximum flow rate calculation unit that calculates a maximum flow rate that is a melt amount per unit time of the resin material based on the melt amount;
Based on the parameter, the physical quantity, and the maximum flow rate, a plasticizing ability calculation unit that calculates a plasticizing ability using a three-dimensional flow calculation;
A plasticization simulation apparatus comprising: A width determination unit that determines whether the solid bed width is equal to or greater than the subflight width based on the parameter and the physical quantity;
When it is determined that the solid bed width is equal to or greater than the subflight width, a height calculation unit that calculates the solid bed height based on the physical quantity;
And a state determination unit that determines whether the solid bed height is in the first state or the second state based on the calculated solid bed height and the parameter. Item 2. The plasticization simulation apparatus according to Item 1. When it is determined that the solid bed height is in the second state,
The height calculation unit calculates the solid bed height each time the amount of melting is calculated,
The state determination unit determines whether the solid bed height exceeds the cylinder height each time the solid bed height is calculated,
When it is determined that the solid bed height exceeds the cylinder height, the physical quantity calculation unit resets the second time step by dividing the second time step by a predetermined value, and calculates the melting amount again. On the other hand, if it is determined that the solid bed height does not exceed the cylinder height and the value of the second time step is less than the first time step, the second time step is multiplied by a predetermined value and melted again. If the solid bed height is determined not to exceed the cylinder height and the value of the second time step is greater than or equal to the first time step, the amount calculated after the most recent second time step resetting is calculated. The plasticization simulation apparatus according to claim 2, wherein the total melting amount is calculated as a true melting amount. Executed by a plasticization simulation apparatus that calculates plasticizing capability based on a three-zone model in which a resin material in a cylinder in a double flight screw type plasticizing apparatus is in a solid bed, melt film, or melt pool state A plasticization simulation method,
Obtaining the parameters including the resin physical properties of the resin material, the operating conditions of the plasticizing device and the configuration data of the plasticizing device having the configuration data of the subflight, and the initial plasticizing capability;
Based on the initial plasticizing capacity, the parameter, the mass conservation formula and the energy conservation formula, the physical quantity including the melting amount is calculated, and the solid bed height is within the cylinder height in the calculation of the melting amount. In the first state, using the first time step, and in the second state where the solid bed height exceeds the cylinder height, using a second time step obtained by dividing the first time step by a predetermined value;
Calculating a maximum flow rate that is a melt amount per unit time of the resin material based on the melt amount;
Calculating plasticizing ability using a three-dimensional flow calculation based on the parameter, the physical quantity, and the maximum flow rate;
A plasticization simulation method characterized by comprising: Plastic that causes the computer to calculate the plasticizing ability based on a three-zone model in which the resin material in the cylinder in the double flight screw type plasticizing apparatus is in a solid bed, melt film, or melt pool state. Computerized simulation program,
The computer,
A parameter including the resin physical properties of the resin material, the operating conditions of the plasticizing device, and the configuration data of the plasticizing device having the configuration data of subflights, and an information acquisition unit for acquiring initial plasticizing capability;
Based on the initial plasticizing capacity, the parameter, the mass conservation formula and the energy conservation formula, the physical quantity including the melting amount is calculated, and the solid bed height is within the cylinder height in the calculation of the melting amount. In the first state, using a first time step, in the second state where the solid bed height exceeds the cylinder height, a physical quantity calculation unit using a second time step obtained by dividing the first time step by a predetermined value;
A maximum flow rate calculation unit that calculates a maximum flow rate that is a melt amount per unit time of the resin material based on the melt amount;
The plasticization simulation program for functioning as a plasticization capability calculation part which calculates plasticization capability using three-dimensional flow calculation based on the parameter, the physical quantity, and the maximum flow rate.

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