JPH0866626A - Agitator - Google Patents

Abstract

PURPOSE: To uniformly agitate a liquid such as a coating material which has high viscosity and whose level is moved up and down in an agitating tank without coagulated lumps being precipitated and without bubbles being caught in the liquid. CONSTITUTION: An agitating blade 1 whose disc is provided with plural notches cut out along the peripheral direction at almost regular intervals and toward around the center from the outer peripheral edge and the back sides of the notches on the back side to the rotating direction of the disc of the notches are bent in the tank bottom side direction to form, and an agitating tank 2 whose tank bottom 2a has the form opposite to that of the back surface of a rotor by the agitating blade 1 are installed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stirring device for uniformly stirring highly viscous liquids such as adhesives and paints.

[0002]

2. Description of the Related Art In general, when a liquid such as an adhesive or a paint is applied to an object, the liquid 16 is circulated through a pump 14 and a filter 15 as shown in FIG. In the step of applying the adhesive or the like, it is necessary to sufficiently stir the liquid 16 returned from the processing tank 13 with the stirrer 12 to keep the ratio of the components contained in the liquid 16 uniform.
Particularly in recent years, the quality of the object 17 to which the liquid 16 is applied has been improved, so that it is necessary to make the coating film uniform at a high level.
If air bubbles or foreign substances are mixed in, there are various inconveniences.

A general stirring device which has been conventionally used is shown in FIGS. 5 (a) to 5 (e). The stirring blades provided in each stirring device are: (a) paddle blade 18, (b) turbine blade 19, (c) propeller blade 20, (d) anchor blade 21,
(e) is called ribbon wing 22. Paddle wing with simple structure 1
8, turbine blades 19, propeller blades 20, etc. are commonly used.

[0004]

When a viscous liquid such as an adhesive is agitated by the conventional agitator (see FIGS. 5 (a) to 5 (e)) introduced above, the following inconveniences occur. There is.

(1) According to the paddle blade 18, the turbine blade 19, and the propeller blade 20, the generation of the flow in the circumferential direction is the center, and the generation of the flow in the radial direction and the axial direction becomes insufficient.
Normally, the propeller blade 20 has an effect of generating an axial flow by the axial thrust due to the rotation of the propeller-shaped blade,
This is because in the case of a liquid with high viscosity, its effect is reduced. Therefore, it is difficult to stir the vicinity of the rotation axis of the stirring blade and the bottom of the stirring tank, and the agglomerates of the liquid and the like precipitate on the bottom of the stirring tank. In particular, the propeller blade 20 tends not to be stirred even near the liquid surface. Here, when the number of rotations of the stirring blade is increased in order to improve these adverse effects and improve the efficiency of stirring by the stirring blade, the flow in the circumferential direction increases and the centrifugal force acting on the liquid increases. Due to such centrifugal force, the central portion of the surface of the liquid stored in the stirring tank is lowered, and bubbles are entrained in the liquid.

(2) Although the anchor blade 21 has the effect of stirring the bottom of the stirring tank to prevent the accumulation of precipitates such as agglomerates, the axial flow is not sufficiently generated, and the axial direction Insufficient stirring.

(3) The ribbon blade 22 excels in axial stirring in a highly viscous liquid, but is inconvenient to handle due to its complicated structure and is inferior in durability. Further, when the liquid level in the stirring tank is lowered due to the consumption of the liquid in the processing tank, the ribbon blade 22 projects from the liquid surface, which causes air bubbles to be caught in the liquid.

As described above, since the conventional stirring devices have different stirring capacities, one stirring device can handle liquids having a high viscosity and a high or low liquid level, such as the vicinity of the rotating shaft and the bottom of the stirring tank. However, it is inconvenient to stir the liquid uniformly over the whole of the above, and without stirring air bubbles in the liquid.

In order to reduce such inconvenience, the following improvement measures are taken.

(A) The stirring blades have individual properties such as stirring by the flow in the direction of the rotation axis and stirring by the flow in the radial direction. Therefore, when both functions are required, the stirring blades are combined in a plurality of stages. Was. As a prior art of this example, there is JP-A-60-64621.

(B) Two kinds of stirring blades having different properties such as stirring by the flow in the direction of the rotation axis and stirring by the flow in the radial direction are incorporated in one stirring blade to deal with the problem. As the prior art of this example, there is JP-A-4-22431.

However, also in (A), since the stirring blades are combined in a plurality of stages, a main stirring blade and an auxiliary stirring blade are required,
The mounting position of the auxiliary stirring blade was restricted so as not to interfere with the movement of the main stirring blade, and there was little freedom in mounting the rotating shaft to the bottom of the stirring tank, and the range of application was narrow. In addition, the structure became complicated, and the labor of disassembling and assembling the stirring blades increased. Further, as for (B), when a highly viscous liquid such as paint is agitated, the flow in the direction of the rotation axis is insufficient like the propeller blade (c), and the agitation at the bottom of the agitation tank and the axial center is sufficient. Not done Therefore, (A) and (B)
Neither of them effectively improves the above-mentioned inconvenience.

The present invention has been made in order to solve the above-mentioned conventional inconvenience, and does not cause precipitation of agglomerates or the like in a liquid having a high viscosity such as a paint and having a liquid level rising and falling in a stirring tank. An object of the present invention is to provide a stirring device capable of stirring uniformly so that air bubbles are not caught in the liquid.

[0014]

In order to achieve the above object, the stirring device of the present invention is a stirring device in which a disk-shaped stirring blade is installed near the bottom of a cylindrical stirring tank. Along the circumferential direction of the agitator, a plurality of notches are provided from the outer peripheral edge to the vicinity of the center at substantially equal intervals, and the rear side of the notches with respect to the rotation direction of the disk is bent toward the bottom of the tank to form the stirring blade. In addition, the bottom of the stirring tank is formed in a shape corresponding to the shape of the lower surface of the solid that is obtained by the rotation of the stirring blade.

According to a second aspect of the invention, in the agitator according to the first aspect, the diameter of the stirring blade is set to 50% to 80% of the diameter of the stirring tank, and the stirring blade is bent. The area of the portion may be set to 8% to 15% of the area of the disk.

According to a third aspect of the present invention, the stirring blades of the stirrer according to the first aspect of the invention have a number of 1 along the circumferential direction of the disc.
It is advisable to provide two notches at 80 ° intervals.

[0017]

According to the stirrer of the present invention having the above-mentioned structure, stirring by a circumferential flow such as the conventional propeller blades and turbine blades is performed for the following reasons for highly viscous liquids such as paint. It is possible to perform stirring by an axial flow such as a ribbon blade and stirring at the bottom of a tank such as an anchor blade. Therefore, it is possible to prevent the generation of a precipitate due to the retention of the liquid, and to keep the composition ratio of the liquid uniform.

The propeller blades generate thrust in the axial direction by rotation, but the effect is small in the case of highly viscous liquid. On the other hand, also in this stirring blade, the same thrust as in the propeller blade is generated by the rotation of the bent portion, but in the case of this stirring blade, except for the small cut portion, the stirring blade is blocked by the disc. The liquid flux cross-section at is small. Therefore, when a rotational speed similar to that of the propeller blade is given, the flow velocity in the axial direction of the stirring blade becomes higher than that of the propeller blade. For this reason, even a highly viscous liquid can be stirred by the axial flow.

In the case of a conventional propeller blade, the circulating liquid is immediately replenished instead of the liquid pushed up by the impeller. However, according to this stirring device, the bottom of the tank is covered by the disk-shaped stirring blade, and between the stirring blade and the tank bottom,
It will be sealed to some extent. Especially in the case of a highly viscous liquid, the hermeticity is high. Therefore, instead of the liquid pushed up by the bent portion, the circulating liquid is not immediately replenished, and the pressure in the portion below the stirring blade becomes low.
Due to this pressure difference, the liquid flows into the bottom of the tank at a relatively high speed from the narrow gap between the disk periphery of the stirring blade and the tank cylinder, and the foreign matter that has settled on the bottom of the tank is rolled up, resulting in sufficient stirring at the bottom of the tank. . Further, since the shape of the rotating body of the stirring blade and the shape of the tank bottom face each other, and the bent portion of the stirring blade and the tank bottom are close to each other, the stirring effect of the tank bottom portion is obtained similarly to the anchor blade. Furthermore, since the center and peripheral portions of the bottom of the tank are raised, precipitates do not accumulate and the place where stirring is likely to be insufficient is compensated.

The portion of the disk-shaped stirring blade that is bent toward the bottom of the tank, along with the stirring due to the axial flow described above,
The effect similar to that of a propeller blade causes a flow in the circumferential direction and enables stirring in the circumferential direction.

Further, according to the present stirring device, bubbles are not entrained in the liquid for the following reason.

Since the stirring blade is installed at a low position in the stirring tank, the stirring blade does not come out to the liquid surface unlike the ribbon blade even when the liquid level goes down.

As described above, according to the present stirring device, since the liquid can be stirred at a relatively low rotation, the flow in the circumferential direction can be suppressed to be small. Therefore, it is possible to avoid the occurrence of vortices, which lowers the liquid surface and entrains bubbles.

In the agitator according to the second aspect of the invention, since the ratio of the disk-shaped agitating blade covering the bottom of the tank, that is, the hermeticity between the agitating blade and the tank bottom is large, the liquid is replenished to the lower part of the agitating blade. The pressure difference also increases due to the difficulty of being applied. Therefore, the velocity of the liquid flowing into the tank bottom through the narrow gap between the disk peripheral edge of the stirring blade and the tank cylinder is high, and the foreign matter settled on the tank bottom can be wound up and the tank bottom can be stirred more effectively.

The stirrer according to claim 3 has a minimum number of cuts. Because if there is only one cut,
This is because the force exerted on the disc-shaped stirring blade becomes uneven, causing a problem at the joint between the stirring blade and the rotating shaft. In addition, since the shape of the bent portion of the stirring blade is constant to some extent because it plays the role of an impeller, in the case of this stirring device, the ratio of the disk-shaped stirring blade covering the bottom of the tank, that is, stirring blade and tank It is easy to increase the tightness between the bottom and the bottom. For this reason, the above-mentioned structure is likely to effectively stir the bottom of the tank.

[0026]

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

FIG. 1 is a plan view of the stirring blade according to this embodiment, FIG. 2 is a front view of the stirring blade of FIG. 1, and FIG. 3 is a sectional view of the stirring device according to this embodiment.

In the stirring blade 1 of this embodiment, as shown in FIG. 1, one disk is provided with cuts 8 from the outer peripheral edge to the vicinity of the center at two positions at 180 ° intervals along the circumferential direction.
Further, of both sides divided by the notch 8, a fixed portion 9 on the rear side with respect to the rotation direction of the disc is bent toward the tank bottom with a straight line 11 passing through the center 10 of the disc as an axis. The bending angle is 45 ° to 90 ° with respect to the disc. This is because the thrust in the axial direction is small at 45 ° or less and the thrust in the axial direction does not occur at 90 ° or more. Also,
As shown in FIG. 2, the lower portion 9a of the bent portion 9 is cut in parallel with the bending shaft 11 so as to follow the shape of the tank bottom 2a. Further, the area of the bent portion 9 of the stirring blade 1 is set to 8% to 15% of the area of the disc. This is because when the ratio is 8% or less, the impeller is too small and the axial stirring due to the axial thrust becomes insufficient, and when it is 15% or more, the above-mentioned hermeticity by the stirring blade 1 is lost. From this viewpoint, the above ratio is preferably 9.5% to 12.5%.

As shown in FIG. 3, the stirring tank 2 of the present embodiment is formed so that a cylindrical tank cylinder 2b is covered with a tank bottom 2a and a tank lid 2c so as to cover the lower surface and the upper surface of the tank cylinder 2b. . Further, the tank bottom 2a is shaped so as to face the shape of the lower surface of the rotating body formed by the stirring blade 1. That is, the bottom 2
The center part and the peripheral part of a are high, and the space between the center part and the peripheral part (around the discharge port 5) is formed low. Further, the tank barrel 2b is provided with a liquid inlet 6, and the tank bottom 2a is provided with a discharge port 5 in a low hollow portion.

In this embodiment, as shown in FIG. 3, the stirring blade 1 is attached to the stirring tank 2 via a rotary shaft 3. The rotary shaft 3 is driven by a variable speed electric motor 4. At this time, the diameter of the stirring blade 1 is set to 20% to 90%, preferably 50% to 80% of the diameter of the stirring tank 2. If the ratio is too small, the above-mentioned stirring blade 1
This is because the airtightness cannot be obtained, and if it is too large, the liquid will not flow to the tank bottom 2a because of too much airtightness. Stirring blade 1
Is installed at a position of about 10 mm to 40 mm from the tank bottom 2a. If it is 40 mm or more, there is no effect of stirring the tank bottom 2a similar to the anchor blade 21 (see FIG. 5), and if it is 10 mm or less, the stirring blade 1 and the stirring tank 2 are too close to each other, and even if the stirring blade 1 slightly shakes. This is because they will come into contact with each other.

The following experiment was conducted with the stirring apparatus according to this example. In the stirring device shown in FIG. 3, the stirring tank 2
And the diameter of the stirring blade 1 was 120 mm, and the lower end of the stirring blade 1 was installed at a height of 30 mm from the tank bottom 2a.
A paint consisting of thermoplastic urethane resin, carbon black, THF (tetrahydrofuran), and MEK (methyl ethyl ketone) was put into the stirring tank 2 up to about half the height, and the rotation speed of the stirring blade 1 was 80 rpm for one week continuously. It was stirred. As a result, during stirring, the paint in the main stirring tank 2 shook on the liquid surface without entraining air bubbles, and no deposit was formed on the tank bottom 2a even after one week. In other words, it can be said that the stirring was sufficiently performed.

On the other hand, the conventional propeller blade 20 (see FIG. 5,
An experiment similar to the above was carried out by using three blades).
As a result, there was almost no shaking of the liquid surface during stirring, and after one week, agglomerates of paint were accumulated on the entire area of the tank bottom 2a, particularly on the peripheral portion, and stirring was insufficient. Therefore, as a result of conducting a similar experiment with the rotating speed of the stirring blade 1 set to 150 rpm, the liquid surface was violently shaken during the stirring, and bubbles were entrained. After one week, no deposit was found near the center of the tank bottom 2a, but the same deposit as above was found at the peripheral edge of the tank bottom 2a. In other words, this did not improve the stirring.

From the above results, according to the stirring apparatus of this embodiment, the conventional propeller blade 20 and turbine blade 1 (see FIG. 5) are used.
In addition to the stirring in the circumferential direction as in 9, the stirring in the axial direction as in the ribbon blade 22 is possible, and the effect of stirring the tank bottom 2a (see FIG. 3) as in the anchor blade 21 is also exerted. Therefore, it is effective for stirring highly viscous liquids such as paints.

[0034]

As is apparent from the above description,
When stirring a highly viscous liquid such as paint, the stirring device of the present invention has the following effects.

(1) The propeller blades generate thrust in the axial direction, but the effect is small in the case of highly viscous liquid. On the other hand, in the case of this stirring blade, the bent portion of the disc generates axial thrust like the above-mentioned propeller blade, but since it is blocked by the disc except for the small cut portion, it is on the same plane as the stirring blade. The cross-sectional area of flux becomes smaller. As a result, when the rotation speed of the stirring blade is the same as that of the propeller blade, the flow velocity in the axial direction becomes higher than that of the propeller blade. For this reason, even a highly viscous liquid can be stirred by the axial flow.

(2) In the case of a normal propeller blade, the circulating liquid is immediately replenished instead of the liquid pushed up by the impeller, but in the case of the present stirring device, a disk-shaped stirring blade is used for the tank. The bottom is covered, and the stirring blade and the bottom of the tank are sealed to some extent. Therefore, instead of the liquid pushed up by the bent portion, the circulating liquid is not immediately replenished, and the pressure in the portion below the stirring blade decreases.
Due to the pressure difference generated at this time, the liquid flows into the tank bottom at a relatively high speed from the narrow gap between the disk peripheral edge of the stirring blade and the tank cylinder,
The result is that the foreign matter settled on the bottom of the tank is rolled up and the bottom of the tank can be sufficiently stirred. Further, since the shape of the rotating body of the stirring blade and the shape of the tank bottom face each other and the bent portion of the stirring blade and the tank bottom are close to each other, the stirring effect of the tank bottom is obtained similarly to the anchor blade. Furthermore, since the center and peripheral portions of the bottom of the tank are raised, precipitates do not accumulate and the place where stirring is likely to be insufficient is compensated.

(3) In the case where the portion of the disc-shaped stirring blade bent toward the tank bottom is a highly viscous liquid exhibiting the same effect as the propeller blade, in addition to the axial flow, the circumferential direction Also causes the flow of. Therefore, stirring in the circumferential direction is also possible.

(4) Since the stirring blade is installed at a low position in the stirring tank, the stirring blade does not come out on the liquid surface unlike the ribbon blade even when the liquid level goes down. Therefore, it is possible to prevent air bubbles from being included in the liquid.

(5) Normally, when the stirring blade is driven at a high speed, a centrifugal force acts and the central portion of the liquid surface is lowered by the vortex.
This causes air bubbles to be entrained in the liquid and causes air bubbles to be entrained by the stirring blade coming out of the liquid surface. On the other hand, according to the present stirring device, the liquid can be stirred at a relatively low rotation speed due to the above-mentioned effect, so that it is possible to prevent bubbles from being trapped in the liquid.

(6) Since the structure of the stirring blade is simple,
Easy to manufacture, handle and maintain.

(7) In the stirrer according to the second aspect of the present invention, since the hermeticity between the stirring blade and the tank bottom is large as described above, the pressure difference due to the difficulty of replenishing the liquid under the stirring blade is also caused. growing. The size of this pressure difference and the narrow gap between the disk periphery of the stirring blade and the tank cylinder combine to increase the velocity of the liquid flowing into the tank bottom, and the foreign matter that has settled at the tank bottom is rolled up and stirred at the bottom of the tank. Can be performed more effectively.

(8) When there is only one cut, the force applied to the disc-shaped stirring blade becomes uneven, and a problem occurs at the joint between the stirring blade and the rotating shaft. , When the number of cuts is minimal. Further, since the bent portion of the stirring blade has a certain constant shape in relation to the role of the impeller, in the case of the present stirring device, the ratio of the stirring blade covering the bottom of the tank, that is, the stirring blade and the tank bottom. It becomes easy to increase the airtightness between them. For this reason, the above-mentioned structure is likely to effectively stir the bottom of the tank.

[Brief description of drawings]

FIG. 1 is a plan view showing a stirring blade according to an embodiment of the present invention.

FIG. 2 is a front view showing the stirring blade of FIG.

FIG. 3 is a sectional view showing a stirring device according to an embodiment of the present invention.

FIG. 4 is a system diagram showing a general process of applying paint or the like.

FIG. 5 is a cross-sectional view showing a conventional general stirring device.

[Explanation of symbols]

 1 Stirring Blade 2 Stirring Tank 3 Rotating Shaft 4 Variable Speed Motor 5 Discharge Port 6 Inlet 7 Stirrer

Claims (3)

[Claims] 1. A stirring device in which a disk-shaped stirring blade is installed near the bottom of a cylindrical stirring tank, wherein a plurality of disk-shaped stirring blades are arranged at substantially equal intervals along the circumferential direction of the disk from the outer peripheral edge to the vicinity of the center. The cutting blade is formed by bending the rear side of the notch with respect to the rotation direction of the disc toward the tank bottom, and the tank bottom of the stirring tank is rotated by the rotation of the stirring blade. An agitator characterized by being formed in a shape corresponding to the shape of the bottom surface of the solid body to be removed. 2. The diameter of the stirring blade is set to 50% to 80% of the diameter of the stirring tank, and the area of the bent portion of the stirring blade is set to 8% to 15% of the area of the disc. The stirrer according to claim 1, which is set. 3. The stirring blade is provided with two notches at 180 ° intervals along the circumferential direction of the disk.
The stirrer described.