JP3097206B2 - Extruder and its control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an extruder for producing a ceramic green sheet or the like by kneading and extruding a semi-fluid raw material.
The present invention relates to an extruder capable of suppressing variation in the size of a molded article and a control method thereof.

[0002]

2. Description of the Related Art Conventionally, when extruding a ceramic green sheet or the like, a kneader is used to knead a ceramic fine powder, a binder, a molding aid, water, and the like at a predetermined ratio in advance to obtain a raw material (earth). ) Is extruded from an extrusion port for molding using an extruder.

A conventional extruder B shown in FIG. 6 is a type of extruder in which a screw having a spiral blade is rotated in a cylinder to extrude while mixing and kneading raw materials. A vacuum chamber 33 between the
Is a two-stage extruder.

In forming a ceramic green sheet using the extruder B, first, a kneaded semi-fluid raw material is charged into a raw material inlet 34. The input raw material (not shown) is supplied to the upper extruding section 31 in which the screw 36 is disposed inside the cylinder 35, and the screw 36
Is extruded into the vacuum chamber 33 and degassed under vacuum. The degassed raw material is compressed by a roller 40 provided at the bottom of the vacuum chamber 33, and then supplied to a lower extruding section 32 in which a screw 38 is disposed in a cylinder 37. , And is extruded as a green sheet from a molding extrusion port 39. However, when the deposition amount of the raw material in the vacuum chamber 33 varies, the load on the roller 40 fluctuates, which affects the extrusion amount of the lower extruding section 32, and the discharge amount from the molding extrusion port 39 is reduced. There is a tendency that the size (for example, the thickness) of the molded product (such as a green sheet) varies.

Therefore, in the above-mentioned conventional extruder B, the load on the roller 40 provided at the bottom of the vacuum chamber 33 is made as uniform as possible, and the extrusion amount of the lower extruding section 32 is made constant to obtain a compact. In order to improve the dimensional accuracy, a deposition amount sensor (for example, a photoelectric switch) 41 for detecting the deposition amount (deposition state) of the raw material is provided in the vacuum chamber 33, and the deposition of the raw material in the vacuum chamber 33 is performed. When the amount exceeds a predetermined position, the rotation amount of the screw 36 of the upper extruding section 31 is switched or turned on and off, so that the amount of the raw material deposited in the vacuum chamber 33 (the deposited state) is kept constant. Like that.

[0006]

However, in the conventional extruder B, the rotational speed of the screw 36 of the upper extruding section 31 is controlled by one point control by one accumulation amount sensor 41 provided in the vacuum chamber. Or switch O
N, so that the vacuum chamber 33
The deposition amount of the raw material in the inside varies, and the deposition amount cannot always be kept sufficiently constant. Therefore, the load applied to the roller 40 at the bottom of the vacuum chamber 33 fluctuates, the load applied to the lower extruding section 32 also fluctuates, the rotational speed of the screw 38 fluctuates, and the discharge amount from the extrusion port 39 for molding fluctuates. However, there is a problem that the thickness of the green sheet varies.

[0007] The present invention solves the above-mentioned problems, and discharge is achieved by maintaining a constant deposition amount of raw material in a vacuum chamber and maintaining a constant load on a roller provided at the bottom of the vacuum chamber. An object of the present invention is to provide an extruder capable of obtaining a molded body such as a green sheet with high dimensional accuracy while keeping the amount constant, and a control method therefor.

[0008]

Means for Solving the Problems To achieve the above object, an extrusion molding machine of the present invention extrudes a semi-fluid raw material such as a ceramic raw material from a molding extrusion port to form a molded article having a predetermined shape. An extruder for molding, comprising: a cylinder disposed substantially horizontally, and a screw having a substantially horizontal screw having a rotating shaft having spiral blades rotating in the cylinder. two extrusion parts, connecting the two extrusion portions, a vacuum chamber roller for material extrusion is provided at the bottom, the upper side
One end of the cylinder that constitutes the extrusion section in the axial direction
The raw material extruded in the axial direction of the cylinder
A vacuum chamber that functions to supply the lower extrusion section ;
A plurality of deposition amount sensors disposed in the vacuum chamber;
At the same height as the center of the outlet of the upper extrusion section,
A syringe that constitutes the upper-stage extrusion section in a horizontal direction from the mouth.
At a distance greater than the inside diameter of the
One deposition amount sensor that detects the deposition amount of the provided raw material
(A first sensor), substantially directly below the first sensor, and above the first sensor.
Less than the lower end of the outlet of the cylinder that constitutes the step side extrusion
One deposition amount sensor (second cell)
Sensor), at substantially the same height as the second sensor, and
Horizontally from the outlet of the cylinder that constitutes the upper extrusion section
At a position approximately the same distance as the inside diameter of the outlet.
Provided with one deposited amount sensor (third sensor)
At least three deposition amount sensors, the first sensor,
Control means for adjusting the number of rotations of the screw of the upper extruding section in accordance with the amount of the raw material detected by at least three deposition amount sensors of the second sensor and the third sensor. .

[0009] The control method of the extruder of the present invention is a control method of the extrusion molding machine according to claim 1, wherein, prior to
The first sensor and the second sensor disposed in the vacuum chamber
And adjusting the number of rotations of a screw of the upper-stage extruding section in accordance with the amount of deposition of the raw material in the vacuum chamber detected by at least three deposition amount sensors of the third sensor to deposit the raw material in the vacuum chamber. The amount is kept within a predetermined range, and the load on the roller at the bottom of the vacuum chamber is made constant.

[0010]

In the extrusion molding machine of the present invention, the height of the outlet in the vacuum chamber is substantially the same as the center of the outlet of the upper extruding section.
From the cylinder that constitutes the upper extrusion section.
Installed at a distance greater than the inside diameter of the mouth
One deposition amount sensor (first sensor) that detects the deposition amount of the raw material
And an upper extruding portion substantially immediately below the first sensor.
Slightly lower than the lower end of the cylinder outlet
One deposited amount sensor (second sensor) and the second sensor
The height is approximately the same as the height
Approximately the same as the inner diameter of the outlet in the horizontal direction from the outlet of the cylinder
Deposition sensor arranged at a position separated by a distance of
(Third sensor), the at least three deposition amount sensors accurately detect the deposition amount (deposition state) of the raw material in the vacuum chamber, and according to the detection result, that is, the deposition state, the upper stage. Since it is configured so that the rotation speed of the screw of the side extrusion unit can be changed, according to the control method of the extrusion molding machine of the present invention, the upper extrusion unit of the upper side extrusion unit according to the deposition state of the raw material in the vacuum chamber. By switching the screw rotation speed to a predetermined rotation speed and driving it, it is possible to keep the deposition amount of the raw material in the vacuum chamber in a predetermined range, and to keep the load on the roller at the bottom of the vacuum chamber constant, child suppress the variation in the discharge amount from the molding extrusion port
Preparative will be able to, it is possible to improve the dimensional accuracy of the results and to moldings.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of the extrusion molding machine of the present invention. The extruder A of this embodiment is an extruder used for extruding a green sheet of ceramics, for example, as shown in FIG. 1, and is provided between an upper extruder 1 and a lower extruder 2. Is a two-stage extruder in which a vacuum chamber 3 is disposed.

The upper extruding section 2 of the extruder A is formed by disposing a screw 6 having spiral blades in a cylinder 5 having a raw material inlet 4 provided at one end thereof. The lower extruding portion 2 is formed by disposing a screw 8 having spiral blades in a cylinder 7 provided with a molding extrusion port 9 at one end thereof. Then, the upper extruding section 1 and the lower extruding section 2
Are connected with a predetermined step (difference in height) by a vacuum chamber 3, and a roller 10 for extruding the raw material from the vacuum chamber 3 to the lower extruding section is provided at the bottom of the vacuum chamber 3.

At predetermined positions in the vacuum chamber 3, three deposition amount sensors 11a, 11b, and 11c (in this embodiment, photoelectric switches) are used to detect the amount of material deposited in the vacuum chamber 3. Is not limited to this), and the accumulation amount sensors 11a, 11
b, 11c are the deposition amounts (deposition state) of the raw materials in the vacuum chamber 3
Is connected to the control means 12 for adjusting the rotation speed of the screw 6 of the upper extrusion section 1 in accordance with

In this embodiment, the accumulation amount sensor 1
1a, 11b and 11c, the deposition sensor (first sensor)
C) 11c is approximately the same height as the center of the outlet of the upper-stage extruding section 1
Thus, the upper extruding section 1 is formed horizontally from the outlet.
Separated by a distance larger than the inner diameter of the outlet of cylinder 5
And a deposition amount sensor (second sensor) 1
1b is substantially below the first sensor 11c,
Slightly lower than the lower end of the outlet of the cylinder 5
And a deposition amount sensor (third cell).
Sensor 11a is approximately the same height as the second sensor 11b,
And the outlet of the cylinder 5 that constitutes the upper extrusion unit 1
Horizontal to the outlet, the same distance as the inner diameter of the outlet
It is located at the location.

Next, the operation (control method) of the extruder A of the present invention configured as described above will be described. In the extruder A shown in FIG. 1, a raw material (not shown) supplied to a raw material input port 4 is supplied to an upper extruding unit 1 and extruded into a vacuum chamber 3 by a rotating screw 6. The raw material extruded into the vacuum chamber 3 is degassed under vacuum,
And is supplied to the lower extruding section 2 thereunder. Then, after being extruded from a molding extrusion port 9 as a green sheet (not shown) as a molded body by the rotation of the screw 8, the green sheet is punched into a predetermined size.

In the above-mentioned extrusion molding process, the deposition amount of the raw material in the vacuum chamber 3 is determined by three deposition amount sensors 11a, 11b,
11c, the accumulation amount sensor 11 is continuously monitored.
The rotation speed (rotation speed) of the screw 6 of the upper extrusion unit 1 is adjusted to a predetermined rotation speed by the control unit 12 in accordance with the amount of deposition (deposition state) of the raw material detected by a, 11b, and 11c. . Table 1 below shows the accumulation amount sensor 11
The relationship between the detection results of a, 11b, and 11c and the rotation speed (rotation speed) of the screw 6 is shown.

[0017]

[Table 1]

That is, as shown in Table 1, when all of the deposition amount sensors 11a, 11b, and 11c are ON (ie, when the raw material M is deposited only up to the position shown in FIG. 2), the upper side The screw 6 of the extrusion unit 1 rotates at high speed. Then, the accumulation amount sensor (third sensor) 11a
Is OFF, the accumulation amount sensor (second sensor) 11b, accumulation
When the quantity sensor (first sensor) 11c is in the ON state (the state in which the raw material M has been deposited to the position as shown in FIG. 3),
The screw 6 rotates at a medium speed. Further, the deposition amount of the raw material increases, and the deposition amount sensor (third sensor) 11a, the deposition amount
Sensor (second sensor) 11b is OFF and the deposition amount sensor
(First Sensor) When only 11c is in the ON state (that is, the state in which the raw material M is deposited up to the position as shown in FIG. 4), the screw 6 rotates at a low speed. Further, when all of the deposition amount sensors 11a, 11b, and 11c are in the OFF state (that is, the state in which the raw material M has been deposited to the position as shown in FIG. 5), the upper screw 6 stops.

In this manner, the plurality of deposition amount sensors 11
a, 11b, and 11c are arranged at predetermined positions in the vacuum chamber 3 to detect and monitor the deposition amount (deposition state) of the raw material, and adjust the rotation speed of the screw 6 of the upper extrusion unit 1 accordingly. Thus, the deposition amount of the raw material in the vacuum chamber 3 can be reliably maintained in a predetermined range, and the variation can be suppressed. As a result, variation in the load on the roller 10 at the bottom of the vacuum chamber 3 is prevented, and the lower extruding section 2 is prevented.
(Ie, the rotation speed of the screw 8 in the lower extruding section) is stable, the variation in the discharge amount from the molding extrusion port 9 is eliminated, and the dimensional accuracy such as the thickness of the green sheet as the molded body is reduced. improves.

Table 2 below shows the relationship between the rotation speed of the screw 8 of the lower extruding section 2 and its variation in the above embodiment (three-point control) together with the data of the aforementioned conventional example (one-point control). .

[0021]

[Table 2]

Further, the molding extrusion port 9 in the above embodiment is used.
Are shown in Table 3 below together with the discharge amount of the above-described conventional example (one-point control).

[0023]

[Table 3]

From the above Tables 2 and 3, in the embodiment of the present invention, the variation in the load on the roller 10 at the bottom of the vacuum chamber 3 is prevented.
It can be seen that the variation in the rotation speed of the screw 8 is small (Table 2), and the stability of the discharge amount from the molding extrusion port 9 is greatly improved (Table 3).

According to the extruder A of this embodiment and its control method, it is possible to sufficiently reduce the variation in the volume of the green sheet, and to reduce the variation in the thickness of the green sheet by half that of the conventional example. It can be suppressed to 1 or less.

In the above embodiment, a two-stage extruder has been described. However, the present invention can also be applied to an extruder having three or more extruders.

In the above embodiment, the case where a sheet-like molded product (green sheet) is extruded has been described. However, the present invention is not limited to the case where the molded product is a sheet-like product. The extruder of the present invention and the control method thereof can be applied to various cases that need to be performed.

[0028]

The extruder according to the present invention has the same height as the center of the outlet of the upper extruding section of the vacuum chamber connecting the extruding sections of the two extruding sections, the upper extruding section and the lower extruding section. , Said out
Cylinder that constitutes the upper extrusion section horizontally from the mouth
At a distance greater than the inner diameter of the outlet
One deposition amount sensor (the first
Sensor), and the upper extruding portion substantially immediately below the first sensor.
Slightly lower than the lower end of the outlet of the forming cylinder
One deposited amount sensor (second sensor)
It is almost the same height as the sensor, and constitutes the upper extrusion section.
Horizontally from the outlet of the cylinder
One deposition volume set at the same distance
And at least three deposition amount sensors provided with a sensor (third sensor). The number of rotations of the screw of the upper extruding section is set to a predetermined value in accordance with the amount of material deposited detected by these deposition amount sensors. so as to drive the switching of the number
Therefore, the deposition amount of the raw material in the vacuum chamber can be reliably maintained in a predetermined range.

As a result, the load applied to the roller at the bottom of the vacuum chamber can be kept constant, the variation in the discharge amount from the extrusion port for molding can be suppressed, and the dimensional accuracy of a molded article such as a green sheet can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an extruder according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view for explaining the operation of the extruder according to the present invention and showing the state of deposition of raw materials in a vacuum chamber.

FIG. 3 is a cross-sectional view for explaining the operation of the extrusion molding machine according to the present invention and showing the state of deposition of raw materials in a vacuum chamber.

FIG. 4 is a cross-sectional view for explaining the operation of the extruder according to the present invention and showing a state of deposition of raw materials in a vacuum chamber.

FIG. 5 is a cross-sectional view for explaining the operation of the extrusion molding machine according to the present invention and showing a state in which raw materials are deposited in a vacuum chamber.

FIG. 6 is a sectional view showing a conventional extruder.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper extrusion part 2 Lower extrusion part 3 Vacuum chamber 5, 7 Cylinder 6 Screw of upper extrusion part 8 Screw of lower extrusion part 9 Extrusion opening 10 Roller 11a, 11b, 11c Deposition amount sensor 12 Control means

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Takashi Kimura 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Inside Murata Manufacturing Co., Ltd. (72) Eikatsu Hayashi 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto In Murata Manufacturing Co., Ltd. (56) References JP-A-56-127411 (JP, A) JP-A-62-259805 (JP, A) JP-A-63-94706 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) B28B 3/20-3/22 B29C 47/92

Claims (2)

(57) [Claims] An extruder for forming a molded body having a predetermined shape by extruding a semi-fluid raw material such as a ceramic raw material from a molding extrusion port , comprising: a cylinder disposed substantially horizontally ; A rotary shaft having a spiral blade rotating in a cylinder has a substantially horizontal screw and an upper-stage extruding unit and a lower-stage extruding unit, which are provided with a substantially horizontal screw. The two extruding units are connected to each other. roller for material extrusion is provided a vacuum chamber, structure the upper side extrusion portion
From one end (outlet) in the axial direction of the cylinder to be formed,
Receiving the raw material extruded in the axial direction of the cylinder,
A vacuum chamber having a function of supplying to the side extrusion section, and a plurality of deposition amount sensors disposed in the vacuum chamber.
At the same height as the center of the outlet of the upper extrusion section,
A syringe that constitutes the upper-stage extrusion section in a horizontal direction from the mouth.
At a distance greater than the inside diameter of the
One deposition amount sensor that detects the deposition amount of the provided raw material
(A first sensor), substantially directly below the first sensor, and above the first sensor.
Less than the lower end of the outlet of the cylinder that constitutes the step side extrusion
One deposition amount sensor (second cell)
Sensor), at substantially the same height as the second sensor, and
Horizontally from the outlet of the cylinder that constitutes the upper extrusion section
At a position approximately the same distance as the inside diameter of the outlet.
Provided with one deposited amount sensor (third sensor)
At least three deposition amount sensors, and at least one of the first sensor, the second sensor, and the third sensor.
An extrusion molding machine, further comprising control means for adjusting the number of rotations of a screw of the upper-stage extruding section in accordance with the amount of material deposited detected by the three deposition amount sensors. 2. The method for controlling an extruder according to claim 1 , wherein the first sensor and the second sensor are disposed in the vacuum chamber.
Depending on the deposition amount of the raw material into the vacuum chamber, which is detected by the service and small without even three deposition amount sensor of the third sensor, by adjusting the rotational speed of the upper-side extrusion of the screw, into the vacuum chamber A method for controlling an extruder, wherein the raw material deposition amount is kept within a predetermined range, and the load on the roller at the bottom of the vacuum chamber is kept constant.