JP2023048722A - Extruder and its control method - Google Patents

Abstract

To prevent or suppress deterioration of appearance quality of an extruded product.SOLUTION: An extrusion apparatus includes: a cylinder through which a material is introduced and conveyed; an agitation part for agitating the material introduced into the cylinder; a detection part to detect a temperature of the cylinder; a heat source to heat the cylinder; and a control part that controls an output of the heat source according to the temperature detected by the detection part. The control part controls the output of the heat source so that a temperature range does not exceed a pressure threshold, which is the pressure applied to the material when it is extruded from the cylinder and is also a threshold for distinguishing an appearance quality.SELECTED DRAWING: Figure 5

Description

The present invention relates to an extruder and its control method.

2. Description of the Related Art Extruders for extruding or injection molding thermoplastic resins are known. For example, there is a screw-type extruder that agitates and extrudes a material such as a thermoplastic resin supplied into a cylinder with a rotating part such as a screw, and feeds the material to a die (see Patent Document 1).

JP-A-10-109351

Generally, in the process of extrusion molding, a resin melted in an extruder is extruded through a die to cover a core wire or to be molded into a tubular shape or the like.

Also, in the extrusion molding process, it was said that the appearance quality of the product was determined (or affected) by the state of the resin in the die during extrusion and the manufacturing conditions.

In relation to this, conventionally, improvement proposals have been proposed from various aspects in order to optimize the manufacturing conditions. On the other hand, there is also the problem that it is difficult to balance the quality of product appearance with other properties of the product, such as tensile strength and outer diameter.

Other problems and novel features will become apparent from the description of the specification and the accompanying drawings.

The extruder of one embodiment comprises:
a cylinder into which the material is introduced and conveyed;
a stirring unit for stirring the material introduced into the cylinder;
a detection unit that detects the temperature of the cylinder;
a heat source for heating the cylinder;
A control unit that controls the output of the heat source according to the temperature detected by the detection unit,
The control unit controls the temperature range so that the temperature range does not exceed a pressure threshold, which is a pressure applied to the material when the material is extruded from the cylinder and is a threshold for classifying the appearance quality. to control the output of

According to one embodiment, it is possible to prevent or suppress deterioration of appearance quality of extruded products.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram explaining the extrusion apparatus of one Embodiment. It is a block diagram explaining the electrical composition of the extrusion device of one embodiment. It is a sectional view for explaining an internal configuration of a screw extruder. 4 is a data table showing the results of experiments conducted by the present inventors regarding appearance quality of resin products manufactured through an extrusion molding process using the extrusion apparatus of the present disclosure. FIG. 5 is a characteristic diagram showing the relationship between the resin pressure value at the cylinder outlet and the quality of product appearance, based on the results of experiments conducted by the present inventors. 6 is a flow chart showing an example of contents of control by a control unit;

An embodiment will be described in detail below with reference to the drawings. In addition, in all the drawings for describing the embodiments, members, devices, and the like having the same or substantially the same functions are denoted by the same reference numerals, and repeated description thereof will be omitted.

<Extruder>
FIG. 1 is a schematic diagram showing an extrusion device according to one embodiment. The extrusion device 1 shown in FIG. 1 extrudes a resin material (hereinafter also simply referred to as “material”) 800 around an electric wire 700 to produce a long tubular covering member (sheath), and produces a final product. A portion of an extrusion apparatus or system for manufacturing cable 900 is shown. Hereinafter, references to "conveying direction" or "extrusion direction" mean the direction in which material 800 is conveyed or extruded, unless otherwise specified.

This extrusion device 1 introduces the material 800 into the conveying path 210 (see FIG. 3), and the extruder 2 that extrudes the introduced material 800 to the downstream side while stirring and heating, and the extruder 2 in the conveying direction. It comprises a crosshead 3 (see FIG. 1) provided downstream and a water tank 5 forming part of a cooling device 200 (see FIG. 2) for cooling the manufactured cable 900 .

FIG. 2 is a block configuration diagram for explaining the electrical configuration of the extrusion device of this embodiment. Although not shown in FIG. 1, elements of the extrusion device 1 include a take-up device 300 for taking the product (cable 900 in this example), a cutting device 400 for cutting the product, and the like (see FIG. 2 for each). . Of these, the take-up device 300 is arranged downstream of the water tank 5 in the transport direction. The cutting device 400 is arranged downstream of the take-off device 300 in the conveying direction. Note that since the take-up device 300 and the cutting device 400 have known configurations, detailed description thereof will be omitted. Also, the electrical configuration of the extruder 2 will be described later.

<Extruder>
FIG. 3 is a partial cross-sectional view for explaining the internal structure of the extruder 2. As shown in FIG. 1 and 3, the extruder 2 includes a tubular cylinder 21 having a conveying path 210, a screw 22 axially rotatable within the conveying path 210 of the cylinder 21, and a screw 22 upstream of the cylinder 21 in the conveying direction. hopper 23, etc., arranged on the side. Hereinafter, the extruder may be referred to as a screw extruder in order to be clearly distinguished from the extruder 1 and the like.

<Cylinder and screw>
The cylinder 21 serves to supply the material 800 (for example, pelletized resin) contained in the hopper 23 into the conveying path 210, compress and heat the supplied material 800, and convey the material 800 in the extrusion direction. Yes, also known as a "barrel".

Although not shown in FIG. 3, the cylinder 21 includes a detection unit 120 (see FIG. 2) such as a temperature sensor and a pressure gauge in order to detect the state (temperature, pressure, etc.) inside the conveying path 210. there is The cylinder 21 also includes a heater 140 (see FIG. 2) as a heat source for heating the material 800 inside the conveying path 210 . Cylinders with such a heat source are also referred to as "heating cylinders".

The screw 22 in the cylinder 21 rotates in a predetermined direction to agitate and compress the supplied material 800 and convey it so as to push it out to the outlet side (right side in FIG. 3) of the conveying path 210 . The screw 22 rotates in a predetermined direction (the direction in which the material 800 is extruded) by transmitting the driving force of the motor (arranged on the left side in FIG. 3), which is an element of the screw driving section 130 shown in FIG.

The main function of the conveying path 210 of the cylinder 21 changes for each area along the conveying direction (extrusion direction) depending on the configuration of the screw 22 and the arrangement of the heater 140 described above. That is, as shown in FIG. 3, the conveying path 210 of the cylinder 21 has different main functions from the upstream side in the conveying direction (extrusion direction) to a feeding section, a compressing section, and a metering section (discharge amount adjusting section). The difference in function of such cylinders along the conveying path 210 is well known, and detailed description thereof will be omitted.

<Crosshead 3>
The crosshead 3 is connected to the outlet side of the cylinder 21 (right side in FIG. 3, front side in FIG. 1). In practice, the crosshead 3 is connected to the cylinder 21 via a connecting member called a “neck” (not shown), so that the transport path (not shown) formed in the head is used for transporting the cylinder 21 . Communicates with path 210 . A die 4 for defining (shaping) the outer shape of the product (sheath in this example) is provided in the crosshead 3 on the downstream side of the conveying path.

The crosshead 3 introduces the molten material 800 sent from the cylinder 21 through the neck, and causes the traveling direction of the introduced material 800 to advance in a direction (for example, substantially perpendicular direction) intersecting the extrusion direction. , and the downstream die 4 to shape the material 800 into a long tubular shape.

Although not shown in FIG. 1, the entrance of the transport path of the crosshead 3 is not only on the connection side with the cylinder 21 described above (in the depth direction in FIG. 1, in other words, the first inlet), but also It also extends in the left direction of the inside as a second inlet. In this embodiment, an electric wire 700 is inserted from the second inlet of the crosshead 3, and a sheath is formed around the electric wire 700 through the die 4, thereby manufacturing a cable 900 as a final product.

<Overview of operations during production of resin extrusions>
An overview of the operation of the extrusion device 1 when manufacturing the cable 900 will be described below.

First, a material 800 in a predetermined shape (pellet shape in this example) is put into the hopper 23 of the extruder 2 . The injected resin drops by gravity and is introduced into the cylinder 21 . The introduced resin is melted in the cylinder 21 and stirred and kneaded by the rotating screw 22 . The kneaded resin (molten state material 800) is conveyed in the extrusion direction indicated by the arrow in FIG. pulled out. In parallel with this operation, an electric wire (a conductor covered with an insulator) 700 passing through the crosshead 3 is covered with a molten material 800 (sheath) inside the crosshead 3 and passes through the die 4. As a result, the cable 900 (final product) is pulled out from the crosshead 3 . The cable 900 is cooled in the water tank 5, taken up by the take-up device 300, and cut by the cutting device 400 to a predetermined length.

<Electrical configuration>
The electrical configuration of the extrusion device 1 will be described with reference to FIG.

As shown in FIG. 2, the extrusion device 1 includes a control unit 100 that controls the entire extrusion device 1, an operation display unit 110 connected to the control unit 100, a detection unit 120, a screw driving unit 130, a heater 140, It includes a recording medium 150, a cooling device 200, a take-up device 300, a cutting device 400, and the like.

The control unit 100 stores a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit), a RAM (Random Access Memory) as a work area of the processor, and a program read and executed by the processor. It includes hardware such as ROM (Read-Only memory).

The control unit 100 has a function of controlling the entire extrusion device 1 by outputting a control signal to each component of the extrusion device 1 . In addition, in the present embodiment, the control unit 100 also has a characteristic function of reading out a table T, which will be described later, and setting the extruder 2 based on the read out table T.

The operation display unit 110 is, for example, a display with a touch panel, displays various setting screens, and accepts user's operation input.

The detection unit 120 includes various sensors such as pressure sensors and temperature sensors. Among them, a plurality of temperature sensors are arranged inside the cylinder 21, and are also arranged in the neck, the crosshead 3, and the die 4 described above. A pressure sensor is arranged, for example, near the outlet of the cylinder 21 .

The screw drive unit 130 includes a motor for rotating the screw 22, a drive circuit for driving the motor, and the like.

The heaters 140 are heat sources such as ceramic heaters, and are arranged at predetermined positions on the cylinder 21 and also on the crosshead 3 .

The recording medium 150 is a medium that stores various data read by the control unit 100, and various data storage media such as HDD and flash memory can be used. The recording medium 150 also stores the table T read by the control unit 100 . Details of the table T will be described later.

<Problems in extrusion equipment and extrusion molding>
By the way, as described above, various improvements have been proposed in order to maintain or improve the appearance quality of the product. For example, there have been proposals to improve product characteristics by optimizing temperature conditions such as cylinder temperature and crosshead temperature.

On the other hand, it is believed that there has been no viewpoint (approach method) of clarifying more preferable manufacturing conditions during extrusion molding by paying attention only to the "appearance" of the product. One of the reasons for this is that the appearance of a product manufactured by extrusion molding is difficult to match with other characteristics of the product (e.g., tensile strength, outer diameter, etc.). The latter characteristic tends to be emphasized more.

From another aspect, in the extrusion apparatus or system described above, the value of pressure at which the resin is extruded from the die 4 (hereinafter referred to as "extrusion parameters”) were adjusted based on the intuition and experience of the operator.

More specifically, it has been empirically known that the above extrusion parameters are important numerical values on which product quality depends. On the other hand, extrusion parameters include other factors related to product quality such as the temperature of each part in the extrusion device, line speed (speed of conveying or taking up material, hereinafter also referred to as “take-up speed”), type of material (during manufacturing condition), it was thought to be a difficult value to set uniformly.

Conventionally, it has been said that the appearance quality of a product is dominated by the shear stress generated in the die 4 during extrusion. Here, the shear stress is calculated from the resin viscosity and shear rate. Viscosity is a function of temperature, and in general, the higher the temperature, the lower the viscosity. On the other hand, the shear rate is determined by the pushing force of the screw 22 and the take-up force of the take-up device 300. Since the latter, that is, the take-up force is usually stronger, Involved.

The present inventors have conducted intensive research and various experiments with respect to the above problem, and have found that the following phenomenon occurs. That is, in the extrusion apparatus 1 configured as described above, in the flow path (conveyance path) until the material 800 such as molten resin (hereinafter sometimes referred to as "molten resin") is sent to the die 4, It has been found that the appearance quality of the resin product molded by the die 4 deteriorates when the pressure applied to the molten resin is excessively increased.

In particular, when the pressure for extruding the molten resin at (near) the exit of the cylinder 21 immediately before the neck of the extruder 2 becomes excessively high, the appearance quality of the resin product extruded and molded from the die 4 is significantly degraded. I found

In addition, the inventors have found that the appearance quality of an extruded product has a low relationship with the line speed (the speed at which the product is pulled out by the take-up device 300), and depending on the conditions, a faster line speed is more advantageous in some cases.

FIG. 4 is a data table showing the results of experiments conducted by the present inventors regarding the appearance quality of resin products manufactured through the extrusion molding process using the extrusion apparatus of the present disclosure. The present inventors set the line speed (m / min), that is, the speed of withdrawal of the product by the take-up device 300 and the rotation speed (rpm) of the screw 22 as variables, and appropriately changed the set temperature of each region in the extruder 1. An experiment was conducted to inspect the appearance quality of products manufactured in In the inspection of appearance quality, the quality of the appearance was determined by visual inspection by a skilled person (accepted product "O" or rejected product "X").

In each experiment, the present inventors determined the temperature of each area in the cylinder, the viscosity of the resin near the outlet of the cylinder 21 ("C5" in the data table), which will be described later, and the discharge amount of the resin. As a parameter (input variable), the pressure applied to the resin at the outlet of the cylinder 21 was obtained by a simulator, and the correlation of each value was considered.

<Common conditions in experiments 1 to 29>
Common conditions in each experiment are described below. In each of Experiments 1 to 29, the inner diameter of the die 4 was 2.4 (mm), and the material 800 was TPU (Thermoplastic Polyurethane) used for electric wires and cables of automobiles.

In the table, C1 to C5 are positions and temperatures of the cylinder 21 along the conveying direction. Specifically, along the conveying direction of the cylinder 21 (extrusion direction in FIG. 3), C1 is the temperature at the most upstream position (near the hopper 23), followed by C2, C3, C4, and so on downstream. and C5 indicates the temperature at the most downstream position (near the outlet). C1 to C5 are in a relationship of approximately equal intervals.

Here, the temperatures (° C.) of C1 to C5 in the table can be actually measured by the temperature sensor in the cylinder 21, but since it is rather difficult to understand if the exact measured values are described, the approximate values actually measured or the settings values are listed. Similarly, the temperatures indicated by N, H, and D in the table are approximate values or setpoints actually measured in the neck, crosshead 3, and die 4 passages (conveyance paths for material 800, etc.), respectively.

Hereinafter, C (1 to 5), N, H, and D in the table may be referred to as "region C1" or "position C1" for convenience.

As shown in the table, in each experiment (1-29), the temperatures of regions C1 and C2 in cylinder 21 were approximately 130° C. and approximately 180° C., respectively. Also, throughout Runs 1-29, the neck (N), crosshead (H), and die (D) temperatures each showed 235°C.

Of the above, the areas C1 and C2 of the cylinder 21 are not provided with the heater 140, and can be said to be areas in which it is difficult to adjust the temperature. On the other hand, regions C3, C4, and C5 of cylinder 21 are regions in which both heaters 140 and temperature sensors are provided and whose temperature can be (easily) adjusted.

Moreover, both a heater 140 and a temperature sensor are provided in the crosshead 3, and the temperature of the neck (N) and the die (D) can be adjusted by the heater 140. 1 to 29), the set temperature was fixed (235° C.) as described above.

In the actual experiments (1 to 29), when the temperature of each region (C1 to D) in the table in the extrusion device 1 became stable so that it was near the set value, the product (cable 900 ) was manufactured.

Furthermore, in Experiments 1 to 29, the appearance quality of the actually manufactured cable 900 (passed product “◯” or rejected product “×”) was determined (determined) by visual inspection by an expert. Furthermore, the "resin pressure" (the pressure value (MPa) applied to the resin extruded from the outlet of the cylinder 21, hereinafter the same) in each experiment was measured using a computer equipped with software for simulating thermal fluid analysis. calculated by

Specifically, this software can calculate the resin pressure by inputting the following (1) to (3) as parameters.
(1) Temperature of each region (five locations from C1 to C5) of cylinder 21 (2) Viscosity of resin when extruded from extruder 2 (cylinder 21) (3) Exit of extruder 2 (cylinder 21) Discharge amount of resin extruded from

The parameters (2) and (3) above are not shown directly in the table of FIG. Of these, the viscosity of the resin in (2) is a function of the temperature (the temperature of the area C5 near the outlet of the cylinder 21 in this example). is determined by the temperature of the region C5 of .

In addition, the discharge amount of the resin in (3) is a function of the linear velocity, and the faster the linear velocity, the greater the discharge amount. Furthermore, the discharge amount of the resin increases as the diameter (mm) of the die 4 increases.

For this reason, the inventors input the temperature (measured or set value) at each position (C1 to C5) of the cylinder 21 as a parameter (1), and set the temperature of the region C5 of the cylinder 21 to the parameter (2). is obtained and input, the value of parameter (3) is obtained from the diameter of the die 4 (2.4 mm in this example) and the setting value of the line speed of the take-up device 300, and is input to the computer, and from the outlet of the cylinder 21 A resin pressure value applied to the extruded material 800 (molten resin) was calculated.

<About variables>
Next, a description will be given of conditions with different values depending on variables, ie, experiments.

As shown in the table in FIG. 4, in Experiments 1 to 10, the temperature conditions (temperature ° C. of regions C1 to D) were the same, the rotation speed (rpm) of the screw 22 was set to a fixed value (15 rpm), and the linear The speed (take-up speed (m/min) by the take-up device 300, hereinafter the same) was set to 10, 12, .

Similarly, in Experiments 11 to 16, the temperature conditions (temperature ° C. of regions C1 to D) were the same as in Experiments 1 to 10, and the rotation speed (rpm) of the screw 22 was slightly slower, 12.5 (rpm). was set to a fixed value, and the linear velocity was set to 18, 20, .

Further, in Experiments 17 to 19, the temperature conditions (temperature ° C. of regions C1 to D) were set to the same values as in Experiments 1 to 16, and the rotational speed (rpm) of the screw 22 was set to a slower fixed value of 10 (rpm). , and the linear velocity was set to 18, 20, 22 (m/min) for each experiment, and increased every 2 (m/min).
Experiment 20, which is an additional experiment, will be described later.

On the other hand, in Experiments 21 to 29 as comparative examples, the temperatures of regions C3, C4, and C5 of cylinder 21 were each set to a low value of 200° C., and the rest was the same as or similar to Experiments 3 to 7 or Experiment 11. conditions (see table in FIG. 4 where appropriate).

More specifically, experiments 21, 22, 23, 24 and 25 were conducted under the same conditions as experiments 3, 4, 5, 6 and 6, respectively, except for the temperature conditions on the downstream side of cylinder 21 described above. gone. On the other hand, in Experiments 26 to 29, based on the results of Experiments 21 to 25, experiments were conducted on the possibility that the appearance quality of the product would be good (○) depending on the combination of linear velocity and rotational speed.

Furthermore, in the above comparative examples (experiments 21 to 29), the appearance quality of the product was all disqualified (x), so the lower limit of temperature (in other words, viscosity ), an additional experiment (experiment 20) was conducted under the same conditions as in experiment 19 except for the temperature condition.

<Experimental results>
The results of Experiments 1 to 29 described above will be described below by dividing them into experimental groups in which the number of rotations (rpm) of the screw 22 is constant.

<Results of Experiments 1 to 10>
In Experiments 1 to 10 in which the number of revolutions (rpm) of the screw 22 was 15 rpm, all products were acceptable (◯) in appearance quality. Also, the resin pressure (MPa) at the outlet of the cylinder 21 has a weak relationship with the linear velocity, and rather the resin pressure (MPa) tended to be higher in Experiments 1 to 3, in which the linear velocity was slower.

<Results of Experiments 11 to 16>
Also in Experiments 11 to 16 in which the number of revolutions (rpm) of the screw 22 was 12.5 rpm, all products were acceptable (◯) in appearance quality. Similarly, it was confirmed that the resin pressure (MPa) at the outlet of the cylinder 21 has little relationship with the line speed.

<Results of Experiments 17 to 19>
In Experiments 17 to 19 in which the number of revolutions (rpm) of the screw 22 was further reduced to 10.5 rpm, all the products were acceptable (◯) in appearance quality. Similarly, the resin pressure (MPa) at the outlet of the cylinder 21 has a weak relationship with the linear speed, and rather it is found that the resin pressure decreases when the linear speed is increased to 20 to 22 (m / min). rice field.

<Results of Experiments 21 to 25>
In Experiments 21 to 25 as comparative examples, all products failed (x) in appearance quality. Also, the resin pressure (MPa) at the outlet of the cylinder 21 showed a high value (approximately 31 to 43 MPa) that can be clearly distinguished from those of Experimental Examples 1 to 19 described above.

<Results of Experiments 26 to 29>
In Experiments 26, 27, 28 and 29 as comparative examples, the temperature conditions were the same as those in Experiments 21 to 25, that is, the temperature on the downstream side of the cylinder 21 was set at 200° C., and the number of rotations of the screw 22 was changed to increase the resin pressure. It was set to 12.5 rpm, the same as in experiments 11-16, which was relatively low. On the other hand, the linear velocity was set to 12 to 18 m/min used in Experiments 2 to 6. However, in Experiments 26-29, all products failed (x) in appearance quality. Also, the resin pressure (MPa) at the outlet of the cylinder 21 showed a high value (approximately 30 to 36 MPa) that can be clearly distinguished from the cases of Experimental Examples 1 to 19 described above.

<Results of additional experiment (experiment 20)>
Based on the results of the comparative examples (experiments 21 to 29), in experiment 20, the linear velocity and the rotation speed of the cylinder 21 were set to be the same as in experiment 19, and the set temperatures of the regions C3, C4, and C5 of the cylinder 21 were gradually increased. As the temperature was lowered, the lower limit temperature at which the appearance quality of the manufactured product was judged to be acceptable (○) was examined. As a result, it was found that even when the set temperatures of the regions C3 to C5 of the cylinder 21 were lowered to 225° C., the appearance quality of the product could be maintained. In this case, the resin pressure (MPa) at the outlet of the cylinder 21 exhibited a value close to that of Experimental Example 18 described above (see FIG. 4 as needed).

Subsequently, the present inventors confirmed the relationship between the resin pressure (MPa) obtained in Experiments 1 to 29 described above and the appearance quality (good or bad), as shown in FIG. A characteristic chart was created. As a result, it was confirmed that the resin pressure (MPa) at the outlet of the cylinder 21 has a threshold for classifying good or bad appearance quality (◯×). In this example, it can be seen that there is a threshold value (pressure threshold value) in the range of approximately 27 to 29 MPa.

For ease of understanding, in the table (characteristic graph) shown in FIG. , and it will be understood that the value of the above pressure threshold remains unchanged in this case as well.
In this way, the present inventors focused only on the appearance of the product manufactured by the extrusion molding process (quality of appearance quality), and conducted experiments and considerations to elucidate more preferable manufacturing conditions during extrusion molding. , found that there is a pressure threshold as described above.

This "pressure threshold" is the pressure value applied to the material 800 when the material 800 passes through the outlet of the cylinder 21, and the appearance quality of the product formed by the downstream die 4 depends on this pressure. is a threshold value for determining whether the quality is good or bad. Specifically, when the pressure applied to the molten resin passing through the outlet of the cylinder 21 exceeds a threshold value (upper limit), the appearance quality of the product shaped by the die 4 is to the extent that human vision can distinguish it. degrades to

In addition, in the experiment of the present inventors, it was not possible to verify the effect on appearance quality when the pressure applied to the molten resin is low. Referring to FIGS. 4 and 5, when the resin pressure is lower than a certain value, the appearance quality is good (○). ” can also be rephrased.

Also, it was found that the "pressure threshold" does not have a strict numerical value as in the case of phase change, for example, but has a certain width (range). From another point of view, the temperature of the material 800 (in other words, Viscosity) can be given some latitude.

Also, through additional experiments, it was found that the "pressure threshold" can vary with the type of material being extruded.

In addition, it has been found that the "pressure threshold" is poorly related to the speed at which the material is extruded (ie line speed or material conveying speed).

In view of the technical significance of the above-described "pressure threshold", it is conceivable to configure the extrusion device or system of the present disclosure as follows. That is, a pressure measuring unit such as a high-performance pressure sensor or pressure gauge is provided at the outlet of the cylinder 21, and an on-off valve for adjusting this pressure is provided. Then, during the operation of the device, the measurement result (pressure measurement value) of the above pressure measurement unit is input to the control unit such as a processor and automatically monitored, and the pressure applied to the molten resin exceeds the threshold (upper limit) If there is a risk, the control unit opens the on-off valve so that the pressure applied to the molten resin does not exceed the pressure threshold.

On the other hand, in the above-described configuration, it is not always easy to finely adjust the pressure applied to the molten resin, and the opening operation of the on-off valve significantly reduces the pressure applied to the molten resin, making extrusion molding itself impossible. There is a possibility that another problem such as disappearance may occur.

Moreover, even if an on-off valve capable of finely adjusting the pressure is used, there is a problem in terms of cost because the existing equipment will need to be modified or additional components will be added. In other words, from the viewpoint of minimizing the occurrence of additional costs, it is desirable to have a configuration that minimizes changes to existing equipment.

Under the background as described above, the present inventors propose the following method and configuration.

(Step 1)
As a preparatory step, an experiment (hereinafter sometimes referred to as a “preliminary experiment”) is conducted to manufacture a test piece of the extruded product as described above with reference to FIG. 4 .

Here, from the temperature conditions of the downstream region (C3, C4, C5 in this example) including the outlet part in the cylinder 21 and the appearance quality of the manufactured test product (○ ×), the temperature is In the experiment in which the appearance quality was good (○) under the lowest conditions, the pressure (resin pressure) applied to the material at the outlet (C5 in this example) in the cylinder 21 was obtained, and the value of the pressure was defined as "pressure threshold”.

It should be noted that it is ideal to conduct this preliminary experiment for each material that is actually used. On the other hand, if the material components are close or similar, it is expected that the pressure threshold values will also be close or similar, so the number of preliminary experiments can be reduced.

(Step 2)
In order to perform automatic processing by the control unit 100, the experimental result in step 1, here the value of the pressure threshold, and the temperature conditions of the downstream regions (C3, C4, C5) including the outlet part in the corresponding cylinder 21 is registered in the table T. This table T is created by assigning a table name (ID, etc.) to each material that is actually used, and as shown in FIG. good.

(Step 3)
During the operation of the apparatus (before the start of operation), the control unit 100 selectively reads the table T corresponding to the materials actually used from the recording medium 150 . This step 3 can be performed, for example, by an input operation using a user interface such as the operation display unit 110 described above with reference to FIG. In response to this input operation, the control unit 100 selects the corresponding table T from the storage medium, and reads out the numerical values (the pressure threshold value and the corresponding temperature condition of the cylinder 21) registered in the table T.

(Step 4)
Subsequently, immediately before starting the operation of the apparatus, the control unit 100, according to the values read from the table T, sets the upper limit value and the Sets the lower limit temperature. Among these, the set lower limit of the temperature corresponds to the above-described pressure threshold.

(Step 5)
After the subsequent start of operation of the device, the control unit 100 drives the heater 140 and each unit, and determines whether the path along which the material 800 is conveyed (each region described above) is within the set temperature range. do. Here, when the control unit 100 determines that all regions are within the set temperature range, it determines that the resin pressure (MPa) applied to the material 800 at the outlet of the cylinder 21 is appropriate. , the determination is repeated while maintaining the output of the heater 140 .

On the other hand, if the control unit 100 determines that there is a region that deviates from the set temperature range, it determines that the pressure applied to the material in that region is not appropriate, and It controls the output of the heater 140 depending on whether it exceeds or not. The details of this control content will be described later in the description of the flowchart.

As described above, the output of the heater 140 is controlled using the pressure threshold, which is the pressure applied to the material 800 when the material 800 is extruded from the cylinder 21 and is the threshold for determining whether the appearance quality is good or bad. According to the disclosed apparatus, it is possible to maintain or improve the appearance quality of extruded products.

In addition, by using the above-mentioned method, the change (in other words, cost increase) from existing equipment can be minimized, the decrease in yield can be suppressed, and the quality of the manufactured extruded product can be maintained at a high level. can be done. Furthermore, when performing control based on the above pressure threshold, the linear velocity can be changed to any speed (see FIG. 5 as appropriate), and productivity can be further improved.

FIG. 6 is a flow chart showing a specific example of control contents of heaters and the like by the control unit. Hereinafter, mainly with reference to FIG. 6, the contents and procedures of control executed by the control unit 100 of the extruder 2 will be described.

In step S1 before the start of operation (setting stage) of the extrusion device 1 (hereinafter sometimes simply referred to as "this device"), the control unit 100 stores in the recording medium 150 according to the setting contents specified by the user. Among the plurality of tables T (T1, T2, . . . , Tn), the table T corresponding to the material used during operation is selected (determined). Then, the control unit 100 reads the numerical values registered in the selected (determined) table T. FIG.

As a specific example, the control unit 100 displays on the display of the operation display unit 110 a setting screen prompting an operation to select the type of the material 800 used in this apparatus, and the type of the material 800 selected by the user's touch operation. Select the table T corresponding to , and read out its numerical value.

In subsequent step S2, the control unit 100 determines the pressure threshold value based on the read numerical value. The determined pressure threshold value is stored in the RAM of the control unit 100 or the like.

More specifically, when the pressure threshold value is described in the table T itself, the control unit 100 determines the described value as the pressure threshold.

On the other hand, when the pressure threshold value itself is not described (explicitly) in the table T as in FIG. .

In one specific example, for example, when the table T has a data structure such as the table described above with reference to FIG. be able to. Alternatively, the control unit 100 sets a value between the maximum value of the resin pressure (MPa) at which the appearance is good (○) and the minimum value of the resin pressure (MPa) at which the appearance is poor (×) (for example, both value) may be calculated and the calculated value may be determined as the pressure threshold. Alternatively, when the initial value of the linear velocity by the take-up device 300 is determined, the control unit 100 determines the maximum value of the resin pressure (MPa) (for example, linear velocity 20 m/ 24 MPa for minutes) may be determined as the pressure threshold.

In step S3 after the pressure threshold is determined as described above, the control section 100 sets a temperature range for product mass production in a predetermined region of the cylinder 21 during operation of the apparatus. In the present embodiment, the control unit 100 controls the temperature (hereinafter referred to as , also called cylinder temperature).

In one non-limiting specific example, the control unit 100 sets the lower temperature limit to 225° C. for each of the regions C3, C4, and C5 of the cylinder 21 . Optionally, the control unit 100 may set an upper temperature limit for the regions C3, C4, C5 of the cylinder 21 . Such an upper limit value may be a predetermined temperature higher than the melting temperature of the material 800 used (for example, a temperature around 235°C).

As described above, temperature sensors are also arranged in other areas (C1 and C2 in this example) of the cylinder 21, but the heaters 140 are not arranged in these other areas. Therefore, the control unit 100 does not set the cylinder temperature (in other words, determine or set the temperature range according to the type of the material 800) for the other region.

In step S4, the control unit 100 starts operating the device. That is, when the motor of the screw drive unit 130 described above starts to drive, the screw 22 in the cylinder 21 rotates, and kneading (stirring) and conveying the material 800 are performed. Also, each heater 140 (heat source) is turned on, heating of each corresponding region of the cylinder 21 is started, and the temperature of the cylinder 21 is measured by the corresponding temperature sensor of the detection unit 120 . Furthermore, the take-up device 300 and the cutting device 400 start operating at appropriate timing.

In step S<b>5 , the control unit 100 receives a change in the line speed, that is, the take-up speed of the take-up device 300 . Here, the control unit 100 outputs a command to that effect to the take-up device 300, for example, when receiving an instruction to increase the line speed by the user's operation input through the operation display unit 110 described above.

At this time, the control unit 100 refers to the registered information (various values relating to the pressure threshold) in the table T, and adjusts the previously determined (set) pressure threshold and the area C3 of the cylinder 21 according to the change in the linear velocity. , C4 and C5 may be changed as appropriate. In addition, the control unit 100 may perform a process of appropriately adjusting the rotational speed of the motor of the screw driving unit 130 (increasing or decreasing the rotational speed) according to the change in linear velocity.

In step S6, the control unit 100 determines that any one of C3, C4, and C5 of the cylinder 21 is higher than the set value (lower limit) of the cylinder temperature based on the measured value of each temperature sensor of the detection unit 120. Determine if there is a risk that the

Here, when the control unit 100 determines that there is no region that may fall below the lower limit (step S6: No), the pressure for pushing out the material 800 at the outlet of the cylinder 21 is good (the pressure threshold is not exceeded). no). In this case, the control unit 100 returns to step S5 and repeats the processes of steps S5 and S6 described above. Therefore, while such processing is being repeated, the line speed can be changed, and the productivity can be increased or the production volume can be adjusted.

On the other hand, when the control unit 100 determines that there is a region where the cylinder temperature may drop below the set lower limit value (step S6: Yes), the pressure for pushing out the material 800 on the outlet side of the cylinder 21 exceeds the pressure threshold value. It is determined that there is a possibility of exceeding, and the process proceeds to step S7.

In step S7, the control unit 100 performs processing to increase the output of the heater 140 (the heat source closest to the region) corresponding to the region where the cylinder temperature may drop below the set lower limit value. By performing such output control (temperature control on the downstream side of the cylinder 21) of the heater 140 (heat source), the pressure for extruding the material 800 at the outlet of the cylinder 21 is kept at a constant value less than the pressure threshold value, and eventually the manufacturing is completed. It is possible to maintain the appearance quality of the product.

In subsequent step S8, the control unit 100 determines whether or not any one of the regions C3, C4, and C5 within the cylinder 21 has reached the upper limit value (for example, 235° C.) of the cylinder temperature.

Here, if the control unit 100 determines that there is no area that has reached the upper limit value (for example, 235° C.) (step S8: No), it repeats the determination in step S8. On the other hand, when the control unit 100 determines that any one of the regions C3, C4, and C5 in the cylinder 21 has reached the upper limit value (step S8: Yes), the process proceeds to step S9.

In step S9, the control unit 100 performs a process of reducing the output of the heater 140 (heat source) corresponding to the area that has reached the upper limit value, and proceeds to step S10.

In step S10, the control unit 100 monitors a user's instruction from the operation display unit 110, for example, and determines whether or not to end the operation of the apparatus.

If the control unit 100 determines not to terminate the operation of the apparatus (step S10: No), the control unit 100 returns to step S5 and repeats the above-described steps S5 to S10.

On the other hand, when the control unit 100 determines to end the operation of the device (step S10: Yes), it transmits an instruction to that effect to the take-up device 300, the cutting device 400, etc., and drives the heater 140 and the screw. The unit 130 is turned off to end the operation.

As described above, according to the extruder (screw extruder) 2 and the extrusion device 1 of the present embodiment, the pressure for extruding the material 800 on the outlet side of the cylinder 21 is kept within a range less than the pressure threshold. It is possible to maintain or improve the appearance quality of the product (electric wire cable in this example).

In addition, according to the extrusion device 1 that performs the above-described series of controls, the line speed can be changed during operation, so in addition to the above effects, productivity can be improved or production can be performed according to the supply status of the material 800. Gender adjustments can be made.

Further, according to the extrusion device 1 that performs the above-described series of controls, it is possible to reduce the output of the heater 140 while maintaining the pressure for extruding the material 800 on the outlet side of the cylinder 21 within a range less than the pressure threshold. , energy saving can be achieved.

In this way, the extruder 2 and the extrusion apparatus 1 of the present disclosure respond so that the pressure applied to the material 800 at the outlet of the flow path (conveyance path) in the cylinder 21 is in a temperature range that does not exceed the pressure threshold. It has a configuration for controlling the output of the heater 140 (heat source). According to this extrusion apparatus 1, there are various advantages such as securing a high level of appearance quality of the manufactured extruded product, improving productivity, and saving energy.

In the embodiment described above, a table T is created and stored in the recording medium 150, in which values relating to the pressure threshold (that is, the pressure threshold itself or various numerical values that can be used to calculate the pressure threshold) are registered for each material 800 used. The configuration is assumed, but not limited to.

As another example, for example, a plurality of sets of values relating to the material 800 to be used and the corresponding pressure threshold values are registered in one table T, and the table T is stored in the recording medium 150, or the memory of the control unit 100 It may also be configured such that it is stored in a .

The material 800 molded by the extrusion device 1 of this embodiment is typically a thermoplastic resin such as polypropylene (PP), polyphenylene sulfide (PPS), acrylic resin, polyester resin, or urethane resin. It is not limited. The material 800 molded by the extrusion device 1 is a material that has the above-described pressure threshold value, that is, the threshold value that is the pressure applied to the material when it is extruded from the cylinder 21 and determines whether the appearance quality is good or bad. I wish I had.

Although the above description assumes that the cable 900 is manufactured, the present invention is not limited to this. Moreover, the shape, size, etc. of the product manufactured by being extruded by the extruder 1 are arbitrary.

The invention made by the present inventor has been specifically described above based on the embodiments, but it should be noted that the present invention is not limited to the above-described embodiments, and that various modifications can be made without departing from the gist of the invention. Not even.

1 Extruder 2 Extruder 3 Crosshead 4 Die 5 Water Tank 21 Cylinder 22 Screw (Stirring Part)
23 hopper 100 control unit 110 operation display unit 120 detection unit (temperature sensor)
130 screw driving unit (stirring unit)
140 heater (heat source)
150 recording medium 200 cooling device 210 conveying path 300 take-up device 400 cutting device 800 material 900 cable (product)
T table

Claims (11)

a cylinder into which the material is introduced and conveyed;
a stirring unit for stirring the material introduced into the cylinder;
a detection unit that detects the temperature of the cylinder;
a heat source for heating the cylinder;
A control unit that controls the output of the heat source according to the temperature detected by the detection unit,
The control unit controls the heat source so that the temperature range does not exceed a pressure threshold, which is a pressure applied to the material when the material is extruded from the cylinder and is a threshold for classifying the appearance quality. controls the output of the
extruder. The extruder of claim 1, wherein
The controller controls the output of the heat source to vary the pressure threshold and the corresponding temperature range depending on the type of material introduced.
extruder. The extruder of claim 1, wherein
The control unit reads out a table in which values relating to the pressure threshold corresponding to the type of the material are registered, and controls the output of the heat source.
extruder. The extruder of claim 3, wherein
In the table, the pressure value applied to the material when the material is extruded from the cylinder and whether the appearance quality is good or bad are registered in association with each other,
The control unit calculates the pressure threshold using each pressure value for which the appearance quality is good.
extruder. The extruder of claim 1, wherein
The control unit sets a temperature range on the outlet side of the cylinder along the extrusion direction so as not to exceed the pressure threshold.
extruder. The extruder of claim 5, wherein
The control unit reads out a table in which values relating to the pressure threshold corresponding to the type of the material are registered, and controls the output of the heat source,
The table includes the pressure value applied to the material when the material is extruded from the cylinder, the temperature on the downstream side of the cylinder along the extrusion direction, and whether the appearance quality is good or bad. and are registered in association with
The control unit controls the output of each of the heat sources provided downstream along the extrusion direction,
extruder. The extruder of claim 1, wherein
The control unit allows the take-up speed to be changed by the take-up device while the extruder is in operation.
extruder. The extruder of claim 1, wherein
The stirring unit is rotatably provided inside the cylinder, and includes a screw that stirs the material and conveys the material so as to push the material toward the downstream side of the conveying path inside the cylinder, and a screw driving unit that rotates the screw. include,
extruder. In an extruder that manufactures a product by conveying the material introduced into the cylinder while heating it with a heat source and extruding it to the outside of the cylinder,
The output of the heat source is controlled so that the temperature range does not exceed the pressure threshold, which is the pressure applied to the material when the material is extruded from the cylinder and is the threshold for distinguishing the appearance quality. ,
Extruder control method. In the extruder control method according to claim 9,
controlling the output of the heat source to vary the pressure threshold and the corresponding temperature range depending on the type of material introduced;
Extruder control method. In the extruder control method according to claim 9,
reading a table in which the pressure threshold value corresponding to the type of material is registered, and controlling the output of the heat source;
Extruder control method.

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