Drawdown stress estimation device, drawdown stress estimation method, and manufacturing method for extrusion molded products

Abstract

To provide a tensile-stress estimating device and a tensile-stress estimating method for estimating tensile-stress of resin.SOLUTION: A tensile-stress estimating device includes a tensile-stress estimating part 304 for estimating tensile-stress based on a constant related to viscosity of a resin and an extrusion condition of the resin.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a technique for estimating the draw stress of a resin. [Background technology]

[0002] Japanese Patent Laid-Open Publication No. 9-262887 (Patent Document 1) describes a technique for predicting changes in specific volume and shrinkage rate by taking into account crystallization during the molding process of a crystalline resin. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-262887 Summary of the Invention [Problem to be solved by the invention]

[0004] A cable has a structure in which the conductor wire is covered with resin to ensure insulation, and the resin covering the conductor wire is formed, for example, by extrusion molding technology. The resin formed by extrusion molding technology is then subjected to an annealing treatment, but it is known that the resin shrinks after the annealing treatment. For example, if the resin shrinks in the longitudinal direction of the cable, there is a risk of the cable becoming wider in outer diameter fluctuation, or of the conductor wire (core wire) becoming exposed from the end of the cable. For this reason, it is desirable to reduce the shrinkage rate of the resin.

[0005] In response to this issue, technology has been developed to reduce the post-shrinkage (shrink-back) of resin that occurs after cable manufacturing. In particular, it has been found that the post-shrinkage of resin after extrusion molding can be reduced by appropriately controlling the extrusion conditions in extrusion molding. For this reason, a shrinkage estimation technology has been developed that estimates the shrinkage rate of resin based on the extrusion conditions.

[0006] With this technology, it is possible to reduce the shrinkage rate of the resin by setting appropriate extrusion conditions, but the material properties of the resin (viscosity and crystallinity) are not taken into consideration. Therefore, if the material properties of the resin change, the extrusion conditions must be optimized each time.

[0007] In other words, since the shrinkage rate of resin is affected not only by extrusion conditions but also by the material properties of the resin, it is desirable to develop technology that can reduce the shrinkage rate of resin by taking into account not only extrusion conditions but also the material properties of the resin. [Means for solving the problem]

[0008] The drawing stress estimation device in one embodiment includes a drawing stress estimation unit that estimates the drawing stress based on Equation 1 and Equation 5 including a constant related to the viscosity of the resin and an extrusion condition of the resin.

[0009] The method for estimating a drawing stress in one embodiment includes a step of estimating the drawing stress based on Equation 1 and Equation 5 including a constant related to the viscosity of the resin and an extrusion condition of the resin.

[0010] In one embodiment, a method for producing an extrusion molded product uses an extruder, and includes a step of estimating a drawing stress applied when a resin is extruded, and a step of changing an extrusion condition of the resin based on the drawing stress, and the drawing stress estimation step estimates the drawing stress based on Equation 1 and Equation 5 including a constant related to the viscosity of the resin and the extrusion condition.

[0011]

number

[0012]

number

[0013] According to one embodiment, the shrinkage rate of the resin can be reduced by taking into account not only the extrusion conditions but also the material properties of the resin. [Brief description of the drawings]

[0014] [Figure 1] 5A to 5C are schematic diagrams illustrating an extrusion molding process for covering the outer periphery of a conductor wire with resin. [Diagram 2] 1 is a schematic diagram showing a state in which a conductor wire is covered with a resin extruded from a die. FIG. [Diagram 3] FIG. 2 is a schematic diagram illustrating “strain rate.” [Figure 4] 1 is a table showing 16 types of experimental conditions (extrusion conditions: temperature, linear speed, rotation speed, outer diameter), the shrinkage rate measured under each of the 16 types of experimental conditions, and the "draw-down stress" estimated based on (Equation 1). [Diagram 5] 1 is a graph showing the relationship between "drawdown stress" and "shrinkage rate." [Figure 6] FIG. 2 is a diagram illustrating an example of a hardware configuration of a shrinkage ratio estimation device. [Figure 7] FIG. 2 is a functional block diagram showing a functional configuration of the shrinkage rate estimation device. [Figure 8] FIG. 1 is a diagram illustrating a configuration for determining a viscosity constant, a temperature coefficient of viscosity, and a viscosity index by machine learning. [Figure 9] FIG. 1 is a diagram illustrating a configuration for determining a response function by machine learning. [Figure 10] 4 is a flowchart illustrating a basic operation of the shrinkage rate estimation device. [Figure 11] 11 is a flowchart illustrating an application operation of the shrinkage ratio estimation device. [Figure 12] 1 is a flowchart illustrating a method for manufacturing an extrusion molded product using a shrinkage rate estimation technique. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] In all the drawings for explaining the embodiments, the same members are generally designated by the same reference numerals, and the repeated explanations thereof will be omitted. In addition, hatching may be applied even to plan views in order to make the drawings easier to understand.

[0016] <Cable manufacturing method> In this embodiment, a process for covering the outer periphery of a conductor with resin using an extrusion molding technique will be described as part of a method for manufacturing a cable in which the conductor is covered with resin.

[0017] FIG. 1 is a schematic diagram illustrating an extrusion molding process for covering the outer periphery of a conductor wire with resin.

[0018] In FIG. 1, raw material pellets 10, which are the raw material of the coating material, are fed into an extruder 11 and kneaded, and molten resin is extruded from a die 13 via a crosshead 12. The extruded resin coats the surface of a conductor 14 moving along a traveling line. The resin coating the surface of the conductor 14 is air-cooled immediately after being extruded from the die 13, and then water-cooled in a water tank 15. In this way, the resin extruded from the die 13 solidifies during the cooling process by air and water cooling. Here, the conductor 14 is composed of copper twisted wire or the like. The raw material pellets (plastic material) 10 are composed of a thermoplastic polyurethane resin or the like.

[0019] The resin formed by the extrusion technique is then annealed, but it is known that the resin shrinks after the annealing process. Since the shrinkage of the resin has an adverse effect on the quality of the cable, it is desirable to reduce the shrinkage rate of the resin.

[0020] Regarding this point, there is a shrinkage rate estimation technique for estimating the shrinkage rate of a resin, but this technique has room for improvement. The room for improvement of this technique will be described below.

[0021] <Room for improvement> For example, it is known that the shrinkage of the resin after molding can be reduced by appropriately controlling the extrusion conditions in the extrusion molding process (such as the temperature of the resin, the linear speed of the conductor wire, and the rotation speed of the screw of the extruder.) For this reason, conventional shrinkage estimation techniques estimate the shrinkage rate based on the input of the extrusion conditions.

[0022] However, since the shrinkage rate of a resin is affected not only by the extrusion conditions but also by the material properties of the resin (viscosity and crystallinity), a technology for estimating the shrinkage rate based solely on the extrusion conditions requires the extrusion conditions to be optimized each time the material properties change.

[0023] Regarding this point, for example, in Patent Document 1 listed in the Background Art, the shrinkage rate is estimated taking into account the crystallinity of the resin. However, the crystallinity is a parameter that needs to be determined by measurement, and it is difficult to apply the technique described in Patent Document 1 in real time, for example, in the cable manufacturing process.

[0024] Thus, the shrinkage rate of a resin depends on both the extrusion conditions and the material properties, but current shrinkage rate estimation techniques do not estimate the shrinkage rate by taking both the extrusion conditions and the material properties into account. This is because, when estimating the shrinkage rate itself, it is difficult not only to take into account both the extrusion conditions and the material properties, but also to develop a shrinkage rate estimation technique that can be introduced in real time into the cable manufacturing process. Therefore, there is a demand for a shrinkage rate estimation technique that can take into account both the extrusion conditions and the material properties and can be introduced into the cable manufacturing process.

[0025] In other words, there is currently room for improvement in terms of providing a shrinkage estimation technique that can be introduced into the cable manufacturing process while taking into account both the extrusion conditions and material properties.

[0026] In the present embodiment, therefore, some improvements have been made to address the above-mentioned room for improvement. The technical concept of this embodiment will be described below.

[0027] <Basic Concept of the Embodiment> The basic idea of ​​the present embodiment is to estimate the shrinkage rate of a resin not by directly estimating the shrinkage rate itself, but by focusing on a physical quantity that is correlated with the shrinkage rate and estimating this physical quantity, the shrinkage rate that is correlated with the physical quantity can be indirectly estimated.

[0028] This basic concept has the following advantages, for example:

[0029] For example, to estimate the shrinkage rate itself with high accuracy, it is necessary to consider both the extrusion conditions and the material properties of the resin. However, in a shrinkage rate estimation technique that formulates the shrinkage rate itself, not only is it difficult to formulate the shrinkage rate itself by considering both the extrusion conditions and the material properties of the resin, but it also includes a parameter called "crystallinity" that needs to be measured. As a result, it is difficult to introduce a technique that formulates the shrinkage rate itself in real time in the manufacturing process of extrusion molded products.

[0030] On the other hand, according to the basic concept, it is not necessary to formulate the shrinkage rate itself, and if a physical quantity that is correlated with the shrinkage rate can be formulated, the shrinkage rate can be indirectly estimated from the formulated physical quantity. In this case, if the formulation of the physical quantity can be easily carried out by considering both the extrusion conditions and the material properties of the resin, and if the formulation can be carried out without including a parameter that requires measurement, such as "crystallinity", the shrinkage rate can be estimated with high accuracy and can be introduced in real time in the manufacturing process of the extrusion molded product. In other words, if a physical quantity that does not include a parameter that requires measurement, such as "crystallinity", as a physical quantity that is correlated with the shrinkage rate, but can be formulated by considering the extrusion conditions and the material properties, is found, the shrinkage rate can be estimated with high accuracy and can be introduced in real time in the manufacturing process of the extrusion molded product.

[0031] Therefore, the inventors of the present invention have conducted extensive research to find such a physical quantity, and as a result have focused on a physical quantity called "drawdown stress." In the following, the "drawdown stress" will be described.

[0032] <"Drawdown stress"> FIG. 2 is a schematic diagram showing how a conductor wire is covered with resin extruded from a die.

[0033] In Fig. 2, molten resin 20 extruded from the outlet of die 13 coats the surface of conductor 14 moving at a constant linear speed. Then, molten resin 20 coated on the surface of conductor 14 is cooled in water tank 15 and crystallized. At this time, as shown in Fig. 2, molten resin 20 extruded from the outlet of die 13 is pulled by conductor 14 moving along the traveling line. As a result, the stress applied in an oblique direction to molten resin 20 from the time it is extruded from the outlet of die 13 to the time it coats conductor 14 is "draw-down stress σ."

[0034] The inventors have focused on the fact that this "draw-down stress" is a physical quantity that can be formulated by taking into account both the extrusion conditions and the material properties, and have attempted to formulate it as shown below. This point will now be explained.

[0035] <Formulation of "Drawdown Stress"> According to the study by the present inventors, the "drawdown stress" is expressed by the following formula 1.

[0036]

number

[0037] Where: σ: Drop stress η 0 : Viscosity constant α: Temperature coefficient of viscosity T: Resin temperature v f : Linear speed L: Distance from the die outlet to the water tank D: Withdrawal ratio n: Viscosity index

[0038] The "withdrawal ratio D" included in (Formula 1) is expressed by (Formula 2) shown below.

[0039]

number

[0040] Where: d w :Die opening diameter d d : Product outer diameter (cable diameter)

[0041] Furthermore, the viscosity constant η 0 ", "temperature coefficient α" and "viscosity index n" are included in the following (Equation 3).

[0042]

number

[0043] Where: η: Viscosity η 0 : Viscosity constant α: Temperature coefficient of viscosity T: Resin temperature dγ / dt: strain rate n: Viscosity index

[0044] <Explanation of strain rate> Here, the "strain rate" included in (Equation 3) will be explained.

[0045] FIG. 3 is a schematic diagram illustrating the "strain rate."

[0046] In FIG. 3, the cross-sectional area of ​​the outlet of the die 13 is indicated by "Sd". The molten resin 20 is extruded from the outlet of the die 13. At this time, the average flow velocity of the molten resin 20 extruded from the outlet of the die 13 is "v d The average flow velocity from the outlet of the die 13 is v d The molten resin 20 extruded at a linear velocity of vf " is added to the "S" shown in Figure 13. f " is the cross-sectional area of ​​a molded product made of a conductor wire coated with molten resin 20. Also, "L" shown in FIG.

[0047] In such a configuration, the "strain rate" is expressed by the following (Equation 4).

[0048]

number

[0049] Where: dγ / dt: strain rate v d : Average flow velocity of molten resin at the die exit v f : Linear speed L: Distance from the die outlet to the water tank

[0050] In other words, the strain rate is the mean flow velocity v d " and linear velocity "v f " is divided by the distance "L" from the outlet of the die 13 to the water tank 15. The "strain rate" defined in this way is, for example, d " and linear velocity "v f " is equal to zero. In other words, the average flow velocity "v d " and linear velocity "v f " is equal to , it can be considered that no distortion is applied to the molten resin 20 qualitatively, and therefore it can be understood that the "strain rate", which is a physical quantity related to the distortion of the molten resin 20, is zero. In addition, the average flow velocity "v d " and linear velocity "v f Since it can be considered that the greater the difference between this and the "strain rate," the greater the strain applied to the molten resin, it is appropriate that the "strain rate" is expressed by (Equation 4).

[0051] <Qualitative understanding of the formulated "drawdown stress"> For example, (Formula 1), which formulates "pull-down stress σ," includes the "viscosity constant η0," "temperature coefficient α," and "viscosity index n," which are all included in (Formula 3) which represents "viscosity η," and the relationship "pull-down stress σ" ∝ "viscosity η" can be derived from (Formula 1) and (Formula 3). In this way, (Formula 1), which formulates "pull-down stress," takes into account the material property of resin viscosity, and since it is thought that qualitatively as viscosity increases, "pull-down stress" also increases, it can be said that the formulation using (Formula 1) is consistent with a qualitative understanding.

[0052] Next, in (Formula 1), the "linear velocity v f ", "Drawdown distance L" and "Drawdown ratio D" are included, which define the extrusion conditions. Therefore, it can be seen that (Formula 1) is a formula that takes into account not only the material property of the resin, namely viscosity, but also the extrusion conditions.

[0053] Here, "linear velocity v f It is believed that as the "pulling speed" (e.g., 5 to 25 m / min) increases, the "pulling stress" increases, and as the "pulling distance L" (e.g., 100 mm) increases, the "pulling stress" decreases. Therefore, in this respect as well, the formulation by (Equation 1) is consistent with the qualitative understanding.

[0054] Furthermore, although it is not clear that the "drawdown ratio D" itself is an extrusion condition, considering that the "drawdown ratio D" is expressed by (Equation 2), it can be understood that the "drawdown ratio D" is related to the screw rotation speed, which is an extrusion condition. That is, when the screw rotation speed of the extruder 11 increases, the amount of resin extruded from the die 13 increases. This means that the thickness of the resin covering the conductor 14 increases, and as a result, the outer diameter of the product increases. This represents that the denominator in (Equation 2) increases, so the "drawdown ratio D" decreases. When the "drawdown ratio D" decreases, the "drawdown stress" increases according to (Equation 1). This can be said to be consistent with the qualitative understanding that the "drawdown stress" is considered to increase when the screw rotation speed of the extruder 11 increases and the amount of resin extruded from the die 13 increases. From the above, it can be said that (Equation 1), which formulates the "drawdown stress", is consistent with the intuitive qualitative understanding and is a valid formulation.

[0055] <The usefulness of the formulated "drawdown stress"> The formula for the "drawdown stress" (Equation 1) has the following usefulness:

[0056] (1) (Equation 1) is a relational equation that takes into account both the material property of the resin, namely the viscosity, and the extrusion conditions, namely the linear speed, the draw-down distance, and the draw-down ratio (corresponding to the screw rotation speed). This makes it possible to estimate the "draw-down stress" with a high degree of accuracy, compared to formulations that only consider the material properties or formulations that only consider the extrusion conditions. This means that if there is a high correlation between the "draw-down stress" and the "shrinkage rate" of the resin, it is possible to estimate the "shrinkage rate" with a high degree of accuracy by considering both the material properties and the extrusion conditions. For this reason, the formulation using (Equation 1) is very significant.

[0057] (2) Next, the formula (Equation 1) of the "drawing stress" does not include the "degree of crystallinity". This is because, as shown in FIG. 2, the resin extruded from the die 13 (for example, the temperature of the resin is 180°C to 200°C) is a molten resin 20, and this molten resin 20 is cooled and crystallized in the water tank 15. Therefore, before reaching the water tank 15, the resin is in a molten state and there is no need to consider the "degree of crystallinity". In other words, the "drawing stress" is significant in that it does not include the "degree of crystallinity" as a parameter. In other words, the formula (Equation 1) of the "drawing stress" that focuses on the "drawing stress" does not include the parameter "degree of crystallinity" that requires measurement, and therefore it can be said to be significant in that it can be easily introduced in real time in the manufacturing process of extrusion molded products.

[0058] However, the above-mentioned usefulness is premised on the assumption that there is a high correlation between the "drawing stress" and the "shrinkage rate". This is because, if there is no high correlation between the "drawing stress" and the "shrinkage rate", even if the "drawing stress" can be estimated with high accuracy by (Equation 1), it does not lead to the "shrinkage rate" being estimated with high accuracy. Therefore, the correlation between the "drawing stress" and the "shrinkage rate" becomes important. In this regard, the present inventor has newly discovered that there is a high correlation between the "drawing stress" and the "shrinkage rate".

[0059] <Reasons for inferring a correlation> First, the reason why the inventor came to presume that there is a correlation between "drawdown stress" and "shrinkage rate" will be explained. The inventor presumed that there is a correlation between "drawdown stress" and "shrinkage rate" as a result of grasping the shrinkage mechanism shown below.

[0060] The shrinkage mechanism that the present inventors have discovered will now be described.

[0061] In the extrusion molding technology, a molten resin extruded from a die is stretched to manufacture a product of a desired size. At this time, the polymer chains of the polymers that constitute the molten resin are stretched due to the "drawdown stress" applied to the extruded molten resin, and the molten resin is water-cooled in the stretched state. When the resin is then exposed to a high temperature again by annealing, the "drawdown stress" applied to the resin is eliminated, and the resin shrinks. The resin shrinks due to the above mechanism. Therefore, according to this mechanism, it can be seen that the "drawdown stress" is one of the factors that cause the resin to shrink. Taking this into consideration, the inventor has come to surmise that there is a correlation between the "drawdown stress" and the "shrinkage rate".

[0062] Below, we will explain the verification results that support the correctness of the inventor's findings, that is, the verification results that support the existence of a high correlation between "drawdown stress" and "shrinkage rate".

[0063] <Correlation verification results> In order to verify the correlation between "draw-down stress" and "shrinkage rate," an extrusion experiment is carried out using, for example, an extrusion molding system having the configuration shown in FIG. 1. Specifically, in the extrusion experiment, a thermoplastic polyurethane resin is used, and the extrusion conditions are the resin temperature, the wire linear speed, and the screw rotation speed. The multiple samples obtained by carrying out the extrusion experiment under each extrusion condition are each cut to 500 mm, and then each of the multiple samples is annealed at 130°C for 3 hours. The amount of shrinkage of each of the multiple samples is then evaluated by measuring the amount of shrinkage of the resin after the annealing treatment.

[0064] On the other hand, the "viscosity constant η0", "temperature coefficient α", and "viscosity index n" are determined from the viscosities measured for each of the samples using (Formula 3), and then these determined constants are substituted into (Formula 1). Specifically, the temperature is changed from 185°C to 210°C, and the viscosity is measured with a capillary rheometer when the strain rate is changed from 6.08 (1 / s) to 6080 (1 / s), and based on these measurement results, the "viscosity constant η0", "temperature coefficient α", and "viscosity index n" are determined from (Formula 3). The constants determined in this way are substituted into (Formula 1), and each extrusion condition (temperature, linear speed, screw rotation speed) is substituted into (Formula 1) to estimate the "drawdown stress". At this time, the "drawdown ratio D" included in (Formula 1) is related to the screw rotation speed, but in reality, it is determined based on the diameter of the die opening and the outer diameter of the sample obtained in the experiment based on (Formula 2).

[0065] The number of samples is equal to the number of three lots with different material properties (viscosity properties) applied to the 16 types of experimental conditions (Experiment No. 1 to Experiment No. 16) shown in Fig. 4. In other words, the number of samples is 16 x 3 = 48 types.

[0066] Fig. 4 is a table showing 16 types of experimental conditions (extrusion conditions: temperature, linear speed, rotation speed, outer diameter), the shrinkage ratio measured under each of the 16 types of experimental conditions, and the "pull-down stress" estimated based on (Equation 1). The 16 types of experimental conditions shown in Fig. 4 are, for example, 16 types of conditions optimized by the "Box-behnken method". This "Box-behnken method" is a method that can find experimental conditions that are sufficient to obtain a highly accurate prediction and can minimize the number of experiments, and the 16 types of experimental conditions shown in Fig. 4 are the minimum necessary conditions found by the "Box-behnken method".

[0067] Next, the experimental results based on the above-mentioned 16×3=48 types of samples will be described.

[0068] FIG. 5 is a graph showing the relationship between "pulling stress" and "shrinkage rate." In FIG. 5, the horizontal axis shows the "pulling stress" estimated based on (Equation 1), while the vertical axis shows the "shrinkage rate" measured in an experiment. In FIG. 5, "Sample A," "Sample B," and "Sample C" correspond to three different lots with different material properties (viscosity properties), and experiments were conducted under 16 different experimental conditions for each of "Sample A," "Sample B," and "Sample C." As a result, there are 3×16=48 measurement points in FIG. 5.

[0069] As a result of examining the graph shown in Figure 5, the correlation coefficient between "drawdown stress" and "shrinkage rate" is "0.8057". Considering that the closer the correlation coefficient is to 1, the higher the correlation, it is clear that there is a high correlation between "drawdown stress" and "shrinkage rate".

[0070] The above experimental results support the existence of a high correlation between "drawdown stress" and "shrinkage rate", and confirm the correctness of the inventor's assumption that a high correlation exists between "drawdown stress" and "shrinkage rate." Therefore, it can be seen that the technical idea of ​​estimating the "shrinkage rate" of a resin based on the "drawdown stress" formulated in (Equation 1) is useful in that it takes into account both material properties and extrusion conditions, and that it can be easily introduced in real time into the manufacturing process of extrusion molded products.

[0071] <Configuration of the shrinkage ratio estimation device> A shrinkage rate estimation device that embodies the above-mentioned technical idea will be described below.

[0072] <<Hardware configuration>> First, the hardware configuration of the shrinkage ratio estimation device according to this embodiment will be described.

[0073] Fig. 6 is a diagram showing an example of a hardware configuration of the contraction ratio estimation device 100 according to the present embodiment. Note that the configuration shown in Fig. 6 merely shows an example of the hardware configuration of the contraction ratio estimation device 100, and the hardware configuration of the contraction ratio estimation device 100 is not limited to the configuration shown in Fig. 6, and may be another configuration.

[0074] 6, the shrinkage ratio estimation device 100 includes a CPU (Central Processing Unit) 101 that executes a program. The CPU 101 is electrically connected to, for example, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, and a hard disk drive 112 via a bus 113, and is configured to control these hardware devices.

[0075] The CPU 101 is also connected to an input device and an output device via a bus 113. Examples of the input device include a keyboard 105, a mouse 106, a communication board 107, and a scanner 111. Examples of the output device include a display 104, a communication board 107, and a printer 110. The CPU 101 may also be connected to, for example, a removable disk device 108 and a CD / DVD-ROM device 109.

[0076] The shrinkage ratio estimation device 100 may be connected to, for example, a network. For example, when the shrinkage ratio estimation device 100 is connected to other external devices via a network, a communication board 107 constituting a part of the shrinkage ratio estimation device 100 is connected to a LAN (Local Area Network), a WAN (Wide Area Network), or the Internet.

[0077] The RAM 103 is an example of a volatile memory, and the recording media, ROM 102, the removable disk device 108, the CD / DVD-ROM device 109, and the hard disk device 112, are examples of non-volatile memories. The volatile memories and non-volatile memories constitute a storage device of the shrinkage ratio estimation device 100.

[0078] The hard disk device 112 stores, for example, an operating system (OS) 201, a group of programs 202, and a group of files 203. The programs included in the group of programs 202 are executed by the CPU 101 using the operating system 201. The RAM 103 temporarily stores at least a portion of the programs of the operating system 201 and application programs executed by the CPU 101, and also stores various data necessary for processing by the CPU 101.

[0079] A BIOS (Basic Input Output System) program is stored in the ROM 102, and a boot program is stored in the hard disk drive 112. When the shrinkage ratio estimation device 100 is started up, the BIOS program stored in the ROM 102 and the boot program stored in the hard disk drive 112 are executed, and the operating system 201 is started up by the BIOS program and the boot program.

[0080] The program group 202 stores programs that realize the functions of the shrinkage ratio estimation device 100, and these programs are read and executed by the CPU 101. In addition, the file group 203 stores information, data, signal values, variable values, and parameters indicating the results of processing by the CPU 101 as each item of a file.

[0081] The files are recorded on a recording medium such as the hard disk drive 112 or a memory. The information, data, signal values, variable values, and parameters recorded on the recording medium such as the hard disk drive 112 or a memory are read by the CPU 101 into the main memory or cache memory and used for the operations of the CPU 101, such as extraction, search, reference, comparison, calculation, processing, editing, output, printing, and display. For example, during the above-mentioned operations of the CPU 101, the information, data, signal values, variable values, and parameters are temporarily stored in the main memory, registers, cache memory, buffer memory, etc.

[0082] The functions of the shrinkage rate estimation device 100 may be realized by firmware stored in ROM 102, or may be realized by software alone, hardware represented by elements, devices, substrates, and wiring, a combination of software and hardware, or a combination with firmware. The firmware and software are recorded as a program on a recording medium represented by a hard disk drive 112, a removable disk, a CD-ROM, a DVD-ROM, and the like. The program is read and executed by the CPU 101. That is, the program causes the computer to function as the shrinkage rate estimation device 100.

[0083] In this way, the shrinkage ratio estimation device 100 is a computer equipped with the CPU 101 which is a processing device, the hard disk drive 112 and memory which are storage devices, the keyboard 105, mouse 106, and communication board 107 which are input devices, and the display 104, printer 110, and communication board 107 which are output devices. The functions of the shrinkage ratio estimation device 100 are realized by utilizing the processing device, the storage device, the input device, and the output device.

[0084] <<Function block configuration>> Next, the functional block configuration of the shrinkage ratio estimation device 100 will be described.

[0085] FIG. 7 is a functional block diagram showing the functional configuration of the shrinkage ratio estimation device.

[0086] In FIG. 7, the shrinkage ratio estimation device 100 in this embodiment has an input unit 301, a constant determination unit 302, a shrinkage ratio estimation unit 303, a judgment unit 305, a matching condition search unit 306, an output unit 307, and a data storage unit 308.

[0087] The input unit 301 is configured to input, for example, a known data group or a data group shown in FIG. 5. Here, the "known data group" is a data group that associates a combination of the temperature and strain rate of the resin with the viscosity, and is defined as a data group in which the temperature, strain rate, and viscosity of the resin are known. The data group shown in FIG. 5 is defined as a data group that associates "drawdown stress" with "shrinkage rate." These "known data groups" and "data group shown in FIG. 5" are input to the input unit 301 and then stored in the data storage unit 308.

[0088] Next, the constant determination unit 302 is configured to determine the "viscosity constant η0", "temperature coefficient α", and "viscosity index n" included in (Equation 3) based on the known data group stored in the data storage unit 308. Specifically, the constant determination unit 302 is configured to determine the viscosity constant, the temperature coefficient of viscosity, and the viscosity index by learning a neural network with the input being the temperature and strain rate of the resin and the output being the viscosity, using the known data group as teacher data, for example, as shown in FIG. 8. The viscosity constant, the temperature coefficient of viscosity, and the viscosity index determined in this manner are stored in the data storage unit 308.

[0089] Next, the shrinkage rate estimation unit 303 is configured to estimate the shrinkage rate of the resin based on the "drawing stress" applied when the resin is extruded. In other words, the shrinkage rate estimation unit 303 is configured to indirectly estimate the shrinkage rate based on the "drawing stress" that has a correlation with the shrinkage rate. For example, the shrinkage rate estimation unit 303 is configured to estimate the "drawing stress" based on a constant related to the viscosity of the resin and the extrusion conditions of the resin, and includes a drawing stress estimation unit 304.

[0090] The drawing stress estimating unit 304 is configured to estimate the "drawing stress" based on (Equation 1) and (Equation 2). For example, the drawing stress estimating unit 304 estimates the "viscosity constant η 0 ", "temperature coefficient α" and "viscosity index n" are substituted (Equation 1), and the extrusion conditions ("resin temperature T", "linear speed v f "Drawing stress" is estimated by further substituting "Drawing ratio D" defined by "Distance L from the die exit to the water tank" and "Drawing ratio D" defined by (Formula 2) into (Formula 1). The "drawing stress" estimated in this manner is stored in the data storage unit 308.

[0091] The shrinkage rate estimation unit 303 is configured to estimate the shrinkage rate of the resin based on the "drawing stress" estimated by the drawing stress estimation unit 304. For example, since there is a correlation between the "drawing stress" and the shrinkage rate represented by the data group shown in FIG. 5, the shrinkage rate estimation unit 303 is configured to estimate the shrinkage rate from the "drawing stress" by utilizing this correlation. As a specific example, as shown in FIG. 9, the shrinkage rate estimation unit 303 is configured to generate a response function by learning a neural network with the input being the "drawing stress" and the output being the shrinkage rate, using the data group shown in FIG. 5 stored in the data storage unit 308 as teacher data, and to estimate the shrinkage rate from the "drawing stress" whose correspondence with the shrinkage rate is unknown, by using this response function.

[0092] Here, the response function is defined as a function that, when a "drawdown stress" is input, outputs a shrinkage rate corresponding to the input "drawdown stress."

[0093] Next, the determining unit 305 is configured to determine whether or not the shrinkage ratio estimated by the shrinkage ratio estimating unit 303 is equal to or smaller than a preset "threshold value."

[0094] When the judgment unit 305 judges that the shrinkage rate estimated by the shrinkage rate estimation unit 303 is not equal to or less than a preset "threshold value", the matching condition search unit 306 is configured to change the extrusion conditions included in (Formula 1) to re-estimate the "drawing stress", and to search for extrusion conditions (matching conditions) under which the shrinkage rate corresponding to the re-estimated "drawing stress" is equal to or less than the "threshold value".

[0095] The output unit 307 is configured to output, for example, the shrinkage rate estimated by the shrinkage rate estimation unit 303 and the extrusion conditions searched for by the compatible condition search unit 306 .

[0096] The shrinkage ratio estimation device 100 according to the present embodiment is configured as described above.

[0097] <Operation of the shrinkage ratio estimation device (shrinkage ratio estimation method)> Next, the operation of the shrinkage ratio estimation device 100 in this embodiment will be described.

[0098] <<Basic operation>> FIG. 10 is a flowchart illustrating the basic operation of the shrinkage ratio estimation device.

[0099] In FIG. 10, first, when a group of known data is input to the input unit 301 (S101), the input group of known data is stored in the data storage unit 308. Next, the constant determination unit 302 determines a constant related to the material characteristic (viscosity) included in (Equation 3) ("viscosity constant η 0", "temperature coefficient α" and "viscosity index n" are determined (S102). After that, the drawing stress estimation unit 304 estimates the "drawing stress" from (Equation 1) by substituting the constants determined by the constant determination unit 302 (S103) and further inputting the extrusion conditions (S104). Next, the shrinkage rate estimation unit 303 estimates the shrinkage rate of the resin from the "drawing stress" estimated by the drawing stress estimation unit 304 based on the response function (S105). Then, the shrinkage rate estimated by the shrinkage rate estimation unit 303 is output from the output unit 307. In this way, the basic operation of the shrinkage rate estimation device 100 is performed. As a result, the shrinkage rate of the resin can be estimated according to the shrinkage rate estimation device 100.

[0100] <<Application Operation>> Furthermore, in the shrinkage rate estimation device 100, in addition to the basic operation described above, the applied operation described below can also be performed. FIG. 11 is a flowchart explaining the applied operation of the shrinkage rate estimation device. In FIG. 11, when the shrinkage rate of the resin is estimated by performing the basic operation described above (S201), the judgment unit 305 judges whether or not the shrinkage rate estimated by the shrinkage rate estimation unit 303 is equal to or less than a preset "threshold value" (S202). If the shrinkage rate estimated by the shrinkage rate estimation unit 303 is equal to or less than the "threshold value", the output unit 307 outputs a message indicating that the shrinkage rate is equal to or less than the "threshold value" (S205). On the other hand, if the shrinkage rate estimated by the shrinkage rate estimation unit 303 is not equal to or less than the "threshold value", the matching condition search unit 306 changes the extrusion conditions included in (Equation 1) to re-estimate the "drawing stress", and searches for extrusion conditions (matching conditions) under which the shrinkage rate corresponding to the re-estimated "drawing stress" is equal to or less than the "threshold value" (S203). Then, the extrusion conditions found by the matching condition search unit 306 are output from the output unit 307 (S204).

[0101] In this manner, the applied operation is performed in the shrinkage ratio estimation device 100. As a result, according to the shrinkage ratio estimation device 100, even if the shrinkage ratio estimated by the shrinkage ratio estimation unit 303 does not satisfy the predetermined condition, it is possible to present the extrusion condition for making the shrinkage ratio satisfy the predetermined condition.

[0102] By operating the shrinkage ratio estimation device 100 in the above manner, the shrinkage ratio estimation method according to the present embodiment is realized.

[0103] <Shrinkage rate estimation program> The shrinkage ratio estimation method performed by the above-described shrinkage ratio estimation device 100 can be realized by a shrinkage ratio estimation program that causes a computer to execute a shrinkage ratio estimation process.

[0104] For example, in the contraction ratio estimation device 100 configured with a computer shown in Fig. 6, the contraction ratio estimation program in this embodiment can be introduced as one of the programs 202 stored in the hard disk device 112. Then, by having the computer that is the contraction ratio estimation device 100 execute this contraction ratio estimation program, the contraction ratio estimation method in this embodiment can be realized.

[0105] The shrinkage ratio estimation program that causes a computer to execute each process for creating data related to the shrinkage ratio estimation process can be recorded on a computer-readable recording medium and distributed. The recording medium includes, for example, a magnetic storage medium such as a hard disk or a flexible disk, an optical storage medium such as a CD-ROM or a DVD-ROM, or a hardware device such as a non-volatile memory such as a ROM or an EEPROM.

[0106] <Effects of the embodiment> According to the technical idea of ​​this embodiment, the shrinkage rate of the resin is not directly estimated, but the shrinkage rate is indirectly estimated based on the "drawdown stress" which is correlated with the shrinkage rate. This not only makes it possible to estimate the shrinkage rate with high accuracy by easily considering both the material properties and the extrusion conditions, but also makes it unnecessary to consider the parameter "crystallinity" which requires measurement, and therefore has great technical significance in that it provides a shrinkage rate estimation technique which can be introduced in real time in the manufacturing process of extrusion molded products.

[0107] For example, in the past, there was no shrinkage estimation technology that could be introduced in real time in the manufacturing process of extrusion molded products, so the shrinkage was reduced by adjusting the extrusion conditions based on the experience of the workers. In this regard, according to the technical idea of ​​the present embodiment, an objectively accurate shrinkage estimation technology can be introduced into the manufacturing process (manufacturing line) of extrusion molded products without relying on the experience of the workers. As a result, according to the present embodiment, it is possible to reduce the amount of waste of resin materials and extrusion molded products (e.g., cables) and improve production efficiency. In other words, the technical idea of ​​the present embodiment makes it possible to introduce the shrinkage estimation technology into the manufacturing line of extrusion molded products, and as a result, it is possible to obtain a remarkable effect of improving the manufacturing yield of extrusion molded products. Therefore, hereinafter, a manufacturing process of extrusion molded products using the technical idea of ​​the present embodiment will be described.

[0108] <Manufacturing method of extrusion molded products> Fig. 12 is a flow chart for explaining a method for manufacturing an extrusion molded product using the shrinkage estimation technique of this embodiment. In Fig. 12, first, the extrusion conditions are initially set (S301). Next, the shrinkage estimation technique of this embodiment is used. Specifically, (Formula 1) is prepared in which constants related to material properties are substituted, and the initially set extrusion conditions are substituted into this (Formula 1) to estimate the "drawdown stress", and the shrinkage rate is estimated based on this "drawdown stress" (S302). At this time, the basic operation and applied operation described above are performed.

[0109] As a result, if the estimated shrinkage rate is equal to or less than the "threshold value", the initially set extrusion conditions are maintained. On the other hand, if the estimated shrinkage rate is not equal to or less than the "threshold value", the conditions are changed to the suitable conditions (extrusion conditions) presented in the application operation (S303).

[0110] Then, the resin is extruded under the maintained or changed extrusion conditions (S304). After that, the resin is annealed (S305), and the shrinkage rate is measured after a predetermined period of time (1 to 2 days) (S306). If the shrinkage rate is equal to or less than a predetermined value (OK), a non-defective cable is manufactured (S307). On the other hand, if the shrinkage rate is not equal to or less than the predetermined value (NG), a response function that outputs the shrinkage rate from the input "drawdown stress" is reconstructed based on this NG data (S308). That is, the response function is reconstructed by adding the above-mentioned NG data and re-learning the neural network that uses the "drawdown stress" as the input and the shrinkage rate as the output. In this way, the cable manufacturing method of this embodiment is realized.

[0111] According to the manufacturing method of the extrusion molded product in this embodiment, the shrinkage rate estimation technology is introduced into the manufacturing line to estimate the shrinkage rate of the resin in advance, so that the manufacturing yield of the extrusion molded product can be improved. Furthermore, even if the estimated shrinkage rate is "OK", if the finally measured shrinkage rate is "NG", the response function can be reconstructed based on this NG data, thereby improving the estimation accuracy of the shrinkage rate.

[0112] The invention made by the inventor has been specifically described above based on the embodiment thereof. However, it goes without saying that the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the invention.

[0113] The technical ideas of the above embodiments are applicable to a wide variety of resins including plastics and rubbers, but are not limited to thermoplastic polyurethane resins, for example, and are applicable to a wide variety of extrusion forms, including tube extrusion, wire extrusion, and regardless of die shape. [Explanation of symbols]

[0114] 10 Raw material pellets 11 Extruder 12 Crosshead 13 Die 14 Conductor 15. Aquarium 20 Molten Resin 100 Shrinkage ratio estimation device 101 CPU 102 ROM 103 RAM 104 Display 105 Keyboard 106 Mouse 107 Communication Board 108 Removable disk device 109 CD / DVD-ROM device 110 Printer 111 Scanner 112 Hard disk drive 201 Operating Systems 202 Programs 203 Files 301 Input section 302 Constant Determination Section 303 Shrinkage ratio estimation section 304 Pull-down stress estimation section 305 Judgment section 306 Matching Condition Search Unit 307 Output section 308 Data Storage Unit

Claims

1. A drawing stress estimation device that estimates drawing stress applied when extruding a resin, comprising: The drawing stress estimation device includes a drawing stress estimation unit that estimates the drawing stress based on Equation 1 and Equation 5, which include constants related to the viscosity of the resin and extrusion conditions of the resin. [0070] Where: σ: Pull-down stress η ０ :Viscosity constant α: Temperature coefficient of viscosity T: resin temperature v ｆ : Line speed L: Distance from the die outlet to the water tank D: Withdrawal ratio n: viscosity index [0080] Where: S ｄ : Cross-sectional area of ​​the die outlet S ｆ : Cross-sectional area of ​​molded product

2. The pull-down stress estimation device according to claim 1, The viscosity constant, the temperature coefficient of viscosity, and the viscosity index included in the formula 1 are calculated based on the viscosity measurement results and the formula 3 shown below. [0090] Where: η: Viscosity η ０ :Viscosity constant α: Temperature coefficient of viscosity T: resin temperature dγ / dt: strain rate n: viscosity index

3. The pull-down stress estimation device according to claim 2, The pull-down stress estimation device comprises: a known data group input unit for inputting a known data group that associates the combination of the temperature and the strain rate with the viscosity; a constant determination unit that determines the viscosity constant, the temperature coefficient of viscosity, and the viscosity index by learning a neural network that uses the known data group as teacher data and has the temperature and the strain rate as inputs and the viscosity as output; having The drawing stress estimation unit estimates the drawing stress from the extrusion conditions based on the formula 1 in which the viscosity constant, the temperature coefficient of the viscosity, and the viscosity index determined by the constant determination unit are substituted.

4. A method for estimating a drawing stress applied when a resin is extruded, comprising the steps of: The drawing stress estimation method includes a drawing stress estimation step of estimating the drawing stress based on Equation 1 and Equation 5, which include a constant related to the viscosity of the resin and an extrusion condition of the resin. [0089] Where: σ: Pull-down stress η ０ :Viscosity constant α: Temperature coefficient of viscosity T: resin temperature v ｆ : Line speed L: Distance from the die outlet to the water tank D: Withdrawal ratio n: viscosity index ##EQU00011## Where: S ｄ : Cross-sectional area of ​​the die outlet S ｆ : Cross-sectional area of ​​molded product

5. A method for producing an extrusion molded product by extruding a resin using an extruder, comprising the steps of: a drawing stress estimating step of estimating a drawing stress applied when the resin is extruded; and changing an extrusion condition for changing an extrusion condition of the resin based on the pull-down stress, The method for manufacturing an extrusion molded product, wherein the drawing stress estimating step estimates the drawing stress based on Equation 1 and Equation 5, which include a constant related to the viscosity of the resin and the extrusion conditions. ##EQU00012## Where: σ: Pull-down stress η ０ :Viscosity constant α: Temperature coefficient of viscosity T: resin temperature v ｆ : Line speed L: Distance from the die outlet to the water tank D: Withdrawal ratio n: viscosity index ##EQU00013## Where: S ｄ : Cross-sectional area of ​​the die outlet S ｆ : Cross-sectional area of ​​molded product

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