JP7623574B2 - Method and device for measuring and managing the level of mixed raw materials in a vacuum chamber using images - Google Patents

Description

The present invention relates to a method and device for measuring and managing the level of mixed raw materials in a vacuum chamber using images.

In a blast furnace, raw ore and lump coke are fed into the top of the furnace while air is blown in from the bottom. The reducing gas generated from the lump coke and the blown air is blown from the bottom to the top of the furnace, reducing and dissolving the iron oxide in the raw ore. To ensure the ventilation of the reducing gas in the furnace, the raw ore must be strong enough not to be pulverized in the furnace. For this reason, blast furnaces usually use raw materials that have been fired at high temperatures in advance, such as sintered ore or fired pellets.

In response to this, non-calcined agglomerates have been developed that use hydraulic binders such as cement to reduce the energy consumption required for calcination and reduce the amount of carbon dioxide, a greenhouse gas, produced. As the raw material for non-calcined agglomerates, it may be possible to use inferior fine ores that have been considered difficult to sinter and mold into agglomerates.

As described in Patent Document 1, it is possible to incorporate coke fines, which has a small particle size and is difficult to directly charge into a blast furnace, and anthracite, which is inexpensive but has low caking properties and is difficult to turn into coke, as reducing agents into non-calcined agglomerates, and it is expected that the reducing agent ratio in the blast furnace can be reduced. According to the latest findings, it is clear that the effect of reducing the reducing agent ratio in the blast furnace can be maximized by setting the carbon content (T.C.) incorporated in the non-calcined agglomerates to 120 to 200 mass% (equivalent to 15 to 25 mass% in T.C.) of the theoretical carbon amount required to reduce iron oxide to metallic iron.

Hydrates in non-sintered agglomerates formed by the hardening reaction of hydraulic binders are decomposed by an endothermic reaction when heated to approximately 400°C or higher in a blast furnace. This causes the strength of non-sintered agglomerates to decrease significantly in the furnace, raising concerns that they may pulverize. If non-sintered agglomerates pulverize in a blast furnace, it will worsen the air permeability inside the furnace, so a certain level of hot strength is required for non-sintered agglomerates for blast furnaces. On the other hand, if a large amount of hydraulic binder is used to ensure hot strength, the amount of reducing material input to the blast furnace will increase to compensate for the heat lost by the endothermic reaction, which will increase the cost of molten iron.

For these reasons, there is a demand for a manufacturing method for unsintered carbon-containing agglomerates that can achieve the hot strength required for blast furnace use with as little hydraulic binder as possible.

Recently, a manufacturing method that can achieve the hot strength required for blast furnace use has been developed that uses vacuum extrusion to produce unbaked carbon-containing agglomerates for blast furnaces.

As shown in the example of Figure 1, the vacuum extrusion molding machine consists of a first extrusion section (mixing section) and a second extrusion section (extrusion molding section). In addition, the area from the outlet of the first extrusion section (mixing section) to the second extrusion section (extrusion molding section) is vacuum degassed to -40 kPaG or less to ensure the necessary strength of the molded body, and in order to stably continue vacuum extrusion molding, it is necessary to maintain the mixing raw material filling rate inside the mixing section and the extrusion molding section within an appropriate range. The appropriate value for the mixing raw material filling rate of the kneading section is 50 volume% to 90 volume%, and optimally, 50 volume% to 65 volume%. The appropriate value for the mixing raw material filling rate of the extrusion molding section is 50 volume% to 95 volume%, and optimally, 50 volume% to 60 volume%.

Here, if the raw material level in the extrusion molding section rises and the raw material filling rate exceeds 95% by volume, there is a concern that the device may stop or be damaged due to overload. If such a situation occurs, the device will have to be stopped for a long period of time (e.g., several hours to several days) to remove the raw material 20 from inside the device, clean the device, repair the device, etc., and the device's operating rate will drop significantly. Therefore, in order to continue mixing and molding stably, it is important to quickly detect an increase in the raw material filling rate in the extrusion molding section by constantly monitoring the rise in the raw material level.

In a vacuum extrusion molding device, the only place where the level of the raw material in the extrusion molding section can be observed is generally a sight glass installed at the top of the vacuum chamber that connects the kneading section and the extrusion molding section. This is because the extrusion molding section and the vacuum chamber are covered with liners to evacuate the inside of the device, and the internal conditions cannot be observed from the outside. In particular, the extrusion molding section needs to be covered on all sides with strong liners to consolidate the raw material, so a sight glass or the like cannot be installed. In addition, because wet raw material 20 flows inside the extrusion molding section and the vacuum chamber, even if a level meter (contact type or non-contact type) is installed inside the device, the raw material will quickly adhere to the sensor, making accurate measurements impossible.

Typically, the raw material level in the extrusion molding section is monitored periodically and visually by an operator through a viewing window at the top of the vacuum chamber. However, the raw material level in the extrusion molding section can rise to the point where the equipment stops due to overload within a few tens of seconds to a few minutes, so regular monitoring by operators can often result in missed increases in the raw material level or delayed response due to differences in judgment between operators.

In addition, in the prior art, there is a technique for measuring the raw material level using a laser projector and a receiver installed above the observation window (Patent Documents 2 and 3). However, the accuracy of measurements using laser light is easily reduced by dust and steam generated from the raw material 20 inside the device. Furthermore, even if one attempts to simply measure the raw material level in the extrusion molding section using laser light (Patent Documents 2 and 3), the raw material 20 supplied from the kneading section and falling inside the vacuum chamber interferes with the laser light, and the height of the falling raw material 20 is detected, rather than the raw material level in the extrusion molding section, which is what one really wants to know.

Here, in environments where dust and steam are generated, such as those targeted by this invention, it is generally known that microwave level meters and millimeter wave level meters can measure the raw material level with relatively high accuracy. However, even if the laser projector and receiver in Patent Document 2 and Patent Document 3 are simply replaced with a microwave level meter or the like, it is difficult to stably measure the raw material level in the extrusion molding section. This is because, similarly, even when a microwave level meter or the like is used, it is subject to interference from the raw material falling inside the vacuum chamber.

The kneading and molding of non-calcined agglomerates will now be described in detail. In the kneading and molding of powder, the raw material 20 and, if necessary, water are fed into the kneading section, and the powder raw material is kneaded with the kneading blades and screws in the device. The raw material 20 is then extruded in the extrusion molding section in the subsequent process. There are various types of kneading and molding devices, but when kneading and molding the raw material 20 continuously and in large quantities (for example, several tons/hr or more), a non-calcined agglomerate kneading and molding machine is generally used, which is composed of a kneading section 4 that uses kneading blades 4c (sometimes screws) attached to a horizontally installed single-shaft or multi-shaft kneading shaft 4b to knead the raw material 20 while continuously transporting it in the horizontal direction, as shown in the example of Figure 1, and an extrusion molding section 7 that extrudes the raw material 20 from an extrusion molding dam 7d with extrusion molding blades 7c (sometimes screws) to mold it. In the example shown in FIG. 1, the extrusion molding unit 7 transports the mixed raw material inside the casing 7a by extrusion molding blades 7c, which are attached to the rotatable extrusion molding unit shaft 7b.

Next, the difference in structure between the kneading section 4 and the extrusion molding section 7, which is important in managing the raw material level, will be explained. The kneading section 4 has a structure in which the top surface can be opened (open, grating, sight window, easily openable lid, etc.) except for the raw material compaction section 4e that compacts the raw material. Therefore, the raw material level inside the kneading section 4 can be easily observed from the top surface of the device. On the other hand, the extrusion molding section 7 is surrounded by a strong liner on all sides except the vacuum chamber 6 in order to maintain the compaction and vacuum degassing conditions of the raw material 20, and the inside of the device cannot be observed from the top surface of the device. Furthermore, even if a non-contact level meter (e.g., a laser distance meter, a microwave level meter, etc.) is used to measure the raw material level in the extrusion molding section 7 from the sight window 10 at the top of the vacuum chamber 6, as described above, the level meter frequently picks up the height of the raw material 20 falling inside the vacuum chamber 6, so the raw material level in the extrusion molding section 7 cannot be stably and continuously measured. Therefore, when measuring the raw material level in the extrusion molding section 7, a method is required to measure from a limited measurement location (sight window 10) while avoiding false detection due to the mixed raw material 20 falling inside the vacuum chamber 6.

As such, different methods must be used to measure the raw material level in the kneading section 4 and the extrusion molding section 7.

The importance of early detection of an increase in the mixed raw material level in the extrusion molding section 7 is described below. In the extrusion molding section 7, the impact on operations when the mixed raw material filling rate exceeds the upper limit (mixed raw material filling rate > 95%) is much greater than the impact when it falls below the lower limit (mixed raw material filling rate < 50%). The reason for this is that when the mixed raw material filling rate falls below the lower limit and the vacuum degassing conditions are no longer met, there is no need to immediately suspend operations; the mixed raw material filling rate in the extrusion molding section 7 can be easily increased by increasing the amount of mixed raw material supplied from the kneading section 4, and the vacuum degassing conditions can be restored.

Furthermore, if the raw material filling rate falls below the lower limit, the extrusion molding section 7d will no longer be filled with the raw material 20, and the vacuum degassing conditions will no longer be maintained. Therefore, if the vacuum degassing conditions are controlled with a pressure gauge, the drop in the raw material filling rate can be easily and quickly detected. On the other hand, if the raw material filling rate exceeds the upper limit, there is a high concern that the device will stop due to overload or that the vacuum chamber 6 or the extrusion molding section 7 will be damaged. In addition, if the device stops due to overload when the raw material filling rate exceeds the upper limit, it is necessary to suspend operation and spend several to several tens of hours discharging the raw material 20 and cleaning, which will be a major factor in reducing production. Furthermore, if the device is damaged, it may be necessary to suspend operation for a long period of time (for example, several tens of hours to several days) to repair it.

For these reasons, when managing the raw material level in the extrusion molding section 7, a method that can quickly detect an increase in the raw material level is more important than a method that can detect a decrease.

The method of adjusting the level of the kneaded raw material in the extrusion molding section 7 is as described below. The level of the kneaded raw material in the extrusion molding section 7 can be adjusted by changing the rotation speed of the kneading shaft 4b to increase or decrease the supply speed of the kneaded raw material 20 from the kneading weir 4d. For example, if the rotation speed of the kneading shaft 4b is reduced, the supply speed of the kneaded raw material from the kneading weir 4d decreases, and the level of the kneaded raw material in the extrusion molding section 7 decreases. On the other hand, if the rotation speed of the kneading shaft 4b is increased, the supply speed of the kneaded raw material from the kneading weir 4d increases, and the level of the kneaded raw material increases. The level of the kneaded raw material can also be adjusted by changing the rotation speed of the extrusion molding shaft 7b to increase or decrease the discharge speed of the molded body from the extrusion molding weir 7d. For example, if the rotation speed is increased, the discharge speed increases and the level of the kneaded raw material decreases, and if the rotation speed is decreased, the discharge speed decreases and the level of the kneaded raw material increases. Furthermore, if the level of the mixed raw material rises suddenly, the level of the mixed raw material can be lowered relatively quickly (for example, within a few minutes to a few tens of minutes) by temporarily stopping the rotation of the mixing shaft 4b to stop the supply of the mixed raw material to the extrusion molding 7, relaxing the vacuum degassing conditions (for example, from ≦-40 kPaG to 0 kPaG) to improve the fluidity of the mixed raw material 20 in the extrusion molding section 7 and promote the discharge of the mixed raw material from the extrusion molding section 7, or removing the extrusion molding gate 7d (extrusion resistance) to promote the discharge of the mixed raw material from the extrusion molding section 7.

Patent No. 5000402 JP 2000-263540 A Publication number 04-030016

The present invention is directed to a measurement method and device that can quickly determine an increase in the level of mixed raw materials in the extrusion molding section 7 of a vacuum extrusion molding device, and provides a mixed raw material level measurement device and a mixed raw material level management method that use images to detect an increase in the mixed raw material level in the extrusion molding section at an early stage.

In order to solve the above problems,
(1) A raw material mixing inlet, a connecting pipe that leads the raw material to the mixing section, a kneader on which a shaft equipped with a impeller is arranged, a weir through which the raw material is pushed out, a vacuum chamber, and an extrusion molding section are arranged in that order, and a sight glass is arranged at the top of the vacuum chamber, and a light arranged above the sight glass illuminates the raw material mixing in the lower part of the vacuum chamber through the sight glass, and an imaging device arranged above the sight glass takes an image of the raw material mixing level in the lower part of the vacuum chamber, thereby observing the rise in the raw material mixing level and measuring and managing the raw material mixing level in the vacuum chamber.

(2) At that time, it is preferable to place one or more rubber or resin plates hanging downward on the wall surface inside the vacuum chamber, adjust the bottom end of the plate to a predetermined position where the level of the mixed raw material in the extrusion molding section is judged to be the upper limit, and confirm that the bottom end of the rubber or resin plate is pushed up and curved by the mixed raw material to judge whether the level of the mixed raw material in the extrusion molding section has exceeded the upper limit.

(3) It is also preferable to raise the sight glass above the upper end of the kneading section and/or to place a heater in the sight glass to heat it, thereby preventing the mixed raw material from adhering to the sight glass.

(4) Furthermore, the raw material level measurement and management device in the vacuum chamber is characterized in that a raw material inlet, a connecting pipe that guides the raw material to the kneading section, a kneader on which a shaft equipped with an impeller is disposed, a weir through which the raw material is pushed out, a vacuum chamber, and an extrusion molding section are arranged in that order, a sight glass is disposed at the top of the vacuum chamber, a light is disposed above the sight glass, and an imaging device is disposed above the sight glass.

(5) At that time, it is preferable that one or more rubber or resin plates are placed hanging downward on the wall surface inside the vacuum chamber, and their lower ends are adjusted to a predetermined position where the level of the kneaded raw material in the extrusion molding section is determined to be the upper limit, and a monitor is provided to confirm that the lower end of the rubber or resin plate is pushed up and curved by the kneaded raw material, and to determine whether the level of the kneaded raw material in the extrusion molding section has exceeded the upper limit.

(6) It is also preferable that the sight glass is elevated above the upper end of the kneading section and/or that a heater is disposed in the sight glass.

The present invention makes it possible for an operator to easily and frequently check the raw material level in the extrusion molding section 7 from the control room, a task that was previously performed periodically by an operator.

FIG. 2 is a diagram showing a kneading and molding machine comprising a first extrusion section (kneading section) and a second extrusion section (extrusion molding section). FIG. 13 is a diagram showing an example of installation of a camera 11 in a test using an actual device. 1 is a photograph of the extrusion molded portion 7 observed through a viewing window 10. FIG. 1 is a schematic diagram of the present invention method. FIG. 11 is a diagram showing the curved state of a rubber plate 13 photographed on an actual device.

In the past, on-site workers (who are not always near the vacuum extrusion molding device) would periodically (e.g., once every hour) go to the sight glass 10 to visually monitor the raw material level in the extrusion molding section 7. However, in this invention, monitoring can be performed frequently (e.g., once every few minutes to once every 10 minutes) from the control room where the operator is always present. This allows for easy and quick detection and management of increases in the raw material level in the extrusion molding section 7.

First, we tested and examined a method in which the image of the camera installed in the observation window 10 was simply transferred to a monitor in the operation room and monitored by an operator in the operation room. The camera installation method used in this test is shown in Figure 2. An example of the structure near the kneading section 4 of this technology is as shown in Figure 2, and the raw material 20 sent from the mixer 1 is fed into the raw material feed port 2. The raw material 20 fed into the raw material feed port 2 is led to the kneading section 4 through the connecting pipe 3, and is kneaded using the kneading blades 4c provided on the shaft 4b. A raw material compaction section 4e is provided in front of the weir 4d from which the raw material is pushed out. In addition, an internal observation section 4f such as a grating is provided at the top of the kneading section 4, and water can be sprayed from the water nozzle 5 through this section onto the raw material 20 in the casing 4a. A vacuum chamber 6 leading to the extrusion molding section 7 is provided beyond the kneading section 4, and a vacuum pump 8 is connected to this vacuum chamber 6 via a vacuum pump connection pipe 9. The observation window 10 is provided at the top of this vacuum chamber 6.

Here, lighting 12 (light, etc.) and camera 11 are required to capture the image, but there is no particular limit to the type as long as they provide an appropriate amount of light (enough to ensure that the bottom of the extrusion molded portion 7 is clearly visible; a normal LED light, etc., will do) and a pixel count (similar to that of a normal commercially available video camera). It is preferable to use a camera that is suitable for shooting in dark places, such as an infrared camera. The lighting 12 can be installed anywhere above the viewing window 10 as long as it can illuminate the shooting position of the camera 11.

With this method, operators can easily check the monitor from their desks, so monitoring frequency can be improved (approximately once every few to 10 minutes). On the other hand, as described below, it is not easy to determine whether the mixed raw material level has risen, so there is a possibility that the operator watching the image on the monitor may not notice the rise in the mixed raw material level, or the judgment may vary from operator to operator. Therefore, we decided to look into a way to make it easier to determine whether the mixed raw material level has risen.

As a result, we devised a method for determining whether the raw material level in the extrusion molding section 7 is rising, so that the operator can determine at a glance whether the raw material level in the extrusion molding section 7 is rising when checking the image. The details of this method are described below.

1) Difficulty in judging whether the mixed raw material level has risen (disturbance of judgment)
Disturbances that make it difficult to judge whether the level of the mixed raw material in the extrusion molding section 7 has risen will be described. When observing the level of the mixed raw material in the extrusion molding section 7 through the observation window 10, the mixed raw material 20 supplied from the kneading weir 4d always falls inside the vacuum chamber 6, so the lower extrusion molding section 7 can only be seen intermittently. Furthermore, the standard for judging whether the level of the mixed raw material has risen is generally only when the extrusion molding shaft 7b and the extrusion molding blade 7c, which can be seen intermittently, become invisible for a while (for example, for a dozen seconds to several tens of seconds). This is because even if a marker is placed inside the extrusion molding section 7 or the vacuum chamber 6 using a color or protrusion, the mixed raw material 20 will adhere to the inside of the extrusion molding section 7 or the vacuum chamber 6 during long-term operation (for example, for a dozen hours to one day), making the marker invisible (the marker can be seen experimentally (for example, for several tens of minutes to several hours), but not during normal operation). On the other hand, since the extrusion molding shaft 7b and the extrusion molding blades 7c are constantly moving, there is little adhesion of the raw material 20 to be kneaded, and since the raw material 20 is reflected when light is shone on them, this can be confirmed visually.

Figure 3 shows a photograph of the extrusion molding section 7 observed through the observation window 10. Photograph 1) in Figure 3 is a photograph before the raw material 20 is fed into the extrusion molding section 7, and shows the internal mechanism. Photographs 2) and 3) in Figure 3 are photographs of the device operating normally (raw material filling rate of 95% or less). From Figure 3, it can be seen that even if the raw material level is normal, the extrusion molding blades 7c and extrusion molding shaft 7b can only be seen intermittently due to the raw material 20 falling inside the vacuum chamber 6 and the raw material 20 being transported inside the extrusion molding section 7 towards the exit side.

Therefore, currently, an on-site worker must observe the extrusion molding section 7 at the sight glass 10 about once every hour to several hours for several tens of seconds to several minutes to determine whether the mixed raw material level is normal (extrusion molding blades 7c and extrusion molding shaft 7b are visible) or abnormal (extrusion molding blades 7c and extrusion molding shaft 7b are not visible). However, if an operator in the control room tries to perform this monitoring method (which takes several tens of seconds to several minutes to perform one normal/abnormal determination) frequently (for example, once every several minutes to several tens of minutes), the operator will spend too much time looking at the monitor to determine normal/abnormal conditions, which will interfere with other work. Therefore, in order to perform mixed raw material level monitoring frequently by visual inspection of the image, it is necessary to shorten the time required for normal/abnormal determination.

2) Setting of the criterion for judging the raw material level In the present invention, in order to shorten the time required for judging the raw material level (currently several tens of seconds to several minutes), a method was devised in which a rubber plate or the like (natural rubber, synthetic rubber, thin resin, etc. that can be easily bent under load) is hung on the inner wall surface of the vacuum chamber 6. Figure 4 shows an outline of the inventive method.

In Figure 4, rubber plates 13 are installed on both ends of the vacuum chamber 6 (at least on the side where the camera is installed), and their bottom ends are adjusted to be at the upper limit of the raw material level (the position where the raw material filling rate in the extrusion molding section 7 is 95%). This rubber plate 13 is fixed only at the top of the vacuum chamber 6, and the bottom end is free. Therefore, when the raw material level is below the upper limit (normal), it hangs down vertically as shown in 1) in Figure 4.

On the other hand, when the level of the raw material to be kneaded exceeds the upper limit (abnormality), as shown in 2) of Figure 4, the lower end of the rubber plate 13 is pushed up from below by the raw material to be kneaded 20 and curves toward the center of the vacuum chamber 6. Since this rubber plate 13 is always visible during operation, there is no need to keep looking inside the vacuum chamber 6 for a long period of time (tens of seconds to several minutes) to check the curved state of the rubber plate 13. Furthermore, such a rubber plate is generally expected to have the effect of reducing adhesion of the raw material to the wall surface of the vacuum chamber 6.

Figure 5 shows the curved state of the rubber plate 13 photographed on an actual machine. From Figure 5, it can be seen that it is easy to see whether the rubber plate 13 is hanging vertically downward (normal) or curved (abnormal). As a result of the investigation, an operator in the control room can easily (no variability in judgment) and quickly (visual check of the monitor within a few seconds) determine whether the mixed raw material level in the extrusion molding section 7 has exceeded the upper limit by remotely checking the video captured by the camera 11 on a monitor in the control room.

3) Suppression of adhesion to the sight glass 10 In order to continue stable judgment by image for a long period of time, it is preferable to implement measures against adhesion of the raw material to be mixed to the sight glass 10. For example, measures include raising the sight glass 10 to prevent dust scattered from the weir 4d from reaching the sight glass 10, or heating the sight glass 10 to prevent condensation from occurring. It is desirable to secure a raising height of about 10 cm or more, and preferably about 20 cm or more.

On the other hand, if the viewing window 10 is raised too high, it may interfere with other equipment when opening and closing the viewing window 10 for internal cleaning, etc., and manufacturing costs may increase, so a maximum raising height of approximately 30 cm is preferable. There is also a concern that the viewing window 10 may become cloudy due to condensation. Heating the viewing window 10 to approximately 40°C or higher will have the effect of suppressing condensation, but if the viewing window 10 temperature is too high, there is a concern that the heat may damage surrounding equipment such as a level gauge, so it is preferable to raise and control the temperature to a range of approximately 40 to 90°C. Here, the viewing window 10 can be heated by simply placing a general heater (such as a glass heater) around the viewing window 10, and this can be done without blocking the camera's field of view.

4) Method for Adjusting the Raw Material Level If the image of the raw material level can be frequently checked by the above-mentioned means, it is possible to adjust the raw material level by the above-mentioned method for adjusting the raw material level and keep it stable.

REFERENCE SIGNS LIST 1 Mixer 2 Feeding port 3 Connecting pipe 4 Kneading section 4a Casing 4b Kneading shaft 4c Kneading blade 4d Kneading weir 4e Kneading raw material consolidation section (where the raw material is consolidated before the weir and kneading is particularly prominently performed)
4f Internal observation section on the top of the kneader (grating, glass window, opening, etc.)
5 Hydration nozzle 6 Vacuum chamber 7 Extrusion molding section 7a Casing 7b Extrusion molding shaft 7c Extrusion molding blade 7d Extrusion molding gate 8 Vacuum pump 9 Vacuum pump connection tube 10 Viewing window 11 Camera 12 Lighting 13 Rubber plate (natural rubber, synthetic rubber, or thin resin that easily bends under load)
20. Mixing raw materials

Claims (4)

A raw material inlet, a connecting pipe for introducing the raw material to the kneading section, a kneader having a shaft equipped with an impeller, a gate through which the raw material is extruded, a vacuum chamber, and an extrusion molding section are arranged in this order, and a viewing window is arranged at the top of the vacuum chamber,
One or more rubber or resin plates are arranged on the inner wall surface of the vacuum chamber so as to hang downward, and the lower end of each plate is adjusted to a predetermined position where the level of the kneaded raw material in the extrusion molding section is determined to be the upper limit;
A light arranged above the sight glass is used to illuminate the raw material at the lower part of the vacuum chamber through the sight glass, and an image of the raw material level at the lower part of the vacuum chamber is taken by an image pickup device arranged above the sight glass, thereby observing the rise in the raw material level;
This method for measuring and managing the level of mixed raw material in a vacuum chamber is characterized by confirming that the lower end of the rubber or resin plate is pushed up and curved by the mixed raw material, and determining whether the level of the mixed raw material in the extrusion molding section exceeds an upper limit . The method for measuring and managing the level of mixed raw materials in a vacuum chamber as described in claim 1, characterized in that the sight glass is elevated above the upper end of the kneading section and/or a heater is placed in the sight glass to raise the temperature, thereby preventing the mixed raw materials from adhering to the sight glass. The mixing raw material inlet, the connecting pipe that introduces the raw material to the mixing section, the mixer with the shaft equipped with the impeller, the weir through which the raw material is extruded, the vacuum chamber, and the extrusion molding section are arranged in this order.
One or more rubber or resin plates are arranged on the inner wall surface of the vacuum chamber so as to hang down, and the lower end of each plate is adjusted to a predetermined position where the level of the kneaded raw material in the extrusion molding section is determined to be the upper limit,
a peephole is disposed in an upper portion of the vacuum chamber, a light is disposed on the peephole, and an imaging device is disposed on the peephole ;
A mixed raw material level measuring and management device in a vacuum chamber, characterized in that it is equipped with a monitor used to confirm that the lower end of the rubber or resin plate has been pushed up and curved by the mixed raw material and to determine whether the mixed raw material level in the extrusion molding section has exceeded an upper limit . 4. The device for measuring and managing the level of raw materials being mixed in a vacuum chamber according to claim 3 , wherein the sight glass is elevated above the upper end of the kneading section and/or a heater is provided in the sight glass.