JPH0532184Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field] This invention relates to a stirring bar.

More specifically, the present invention relates to a stirring rod that has the function of constantly scraping away liquid that clings to the periphery of a rotating rod and rises due to the Weissenberg effect unique to liquids having viscoelasticity.

The stirring rod of the present invention is particularly useful for stirring viscoelastic liquids, specifically polymer solutions in the polymerization process, or viscous liquids in which polymers are dissolved in solvents or the like.

[Prior Art] A stirrer is a device that is used in most cases when handling liquids, regardless of whether they are for experimental or industrial use, regardless of type, and regardless of high or low viscosity.

The size, shape, method of use, and conditions of use of a stirring rod, which is a part of a conventionally used stirrer, are roughly as follows.

Generally, a small type for laboratory use is a straight round bar with an outer diameter of 5 mm or more, usually 5 to 10 mm, and a length of about 100 to 500 mm.

On the other hand, large industrial ones have an outer diameter of about 10 to 50 mm, depending on the size of the equipment to which they are attached.
It is also a straight round bar with a length of 500mm to 2000mm.

The material is usually made of iron or stainless steel, and it is usually made in one piece, and if the object to be stirred is a special liquid, a glass-lined one may be used.

These stirring rods are used in combination with other parts as described below.

That is, a paddle-type, anchor-type, single or double helical ribbon-type, propeller-type, turbine-type, or faudler-type stirring impeller is fixed to one end of the straight round bar-shaped object, depending on the purpose of use. Ru.

The stirring blade is generally fixed using a mechanical attachment/removal method such as bolts or screws. Further, the vicinity of the other end is held by a bearing, and the tip portion is connected to a drive shaft of a motor, converter, etc. using a coupling.

When using the stirrer with stirring blades combined as described above, the relationship between the depth of the liquid to be stirred in the container and the immersion depth of the stirring blade is approximately as follows.

That is, it is common for the stirring blade to be completely submerged in the liquid.

The reason for this is not only to sufficiently exhibit the stirring effect, but also because if the stirring blade is exposed above the liquid surface, it is unfavorable for the following reasons.

In other words, if the stirring blade stirs near the surface of the liquid, not only will the stirring effect not be sufficiently exerted, but the liquid will also scatter around, causing more liquid to adhere to the inner surface of the container than necessary and causing unnatural bending stress on the stirrer shaft. This is because the stirring blades shake due to the high pressure applied. Additionally, air may be entrained in the liquid, which may impair the properties of the resulting substance.

Needless to say, the purpose of stirring is to homogenize the liquid, so that the reaction occurs uniformly.
A stirrer is also an indispensable piece of equipment in chemical reaction equipment in order to efficiently remove heat or heat.

Particularly when handling highly viscous liquids, natural stirring due to convection of the liquid itself is not possible, so this is especially necessary.

However, the following problems may occur with a simple stirring bar that is a combination of a stirring blade and a stirring shaft as described above.

[Problem that the idea aims to solve] The problem is as follows.

In other words, when stirring a viscoelastic liquid such as a polymer solution undergoing polymerization or a polymer solution dissolved in a solvent, even if the stirring blade is completely immersed in the liquid and rotated, the viscoelasticity will be affected. When a rotating object is placed in a liquid, the liquid will gather around the rotating rod due to the unique Weissenberg effect and the liquid will rise along the stirring rod.

In such a state, for example, there may be parts in the polymer solution during polymerization where polymerization does not proceed uniformly.

This is particularly undesirable when producing a polymer with a uniform molecular weight distribution.

In view of this situation, the present inventor has completed the present invention after intensive study.

[Structure of the invention] That is, the present invention has the following: a screw structure disposed on the outer periphery of a rotating shaft; a rotating shaft that freely rotates with the screw structure while contacting the screw structure; and a screw structure disposed at an end position of the rotating shaft. This stirring bar is characterized by having a structure in which a stirring blade is provided.

The key point of the present invention is that the screw structure has the ability to constantly scrape out the liquid that clings around the rotating rod and rises due to the Weissenberg effect.

Hereinafter, the stirring rod according to the present invention will be described in detail using FIG. 1 (external view) showing one embodiment thereof.

In Figure 1, 1-1 is a screw, 2-2
is a rotating shaft, 3-3 is a stirring blade, 4-4 is a bearing which also serves as a holder for the stirring blade, and 5-5 is a bridge connecting the screw and the bearing. However, 4-
The bearing portion 4 is not an essential component in the present invention. The rotating shaft 2-2 is inserted through the screw 1-1, and rotates freely relative to each other, and the inner surface of the screw constantly slides on the surface of the rotating shaft, that is, the liquid that clings and rises. It must be precisely machined so that it rotates closely so that it can perform the function of constantly scraping away the water. The material for making the screw 1-1, the bridge and bearing connected thereto is not particularly limited, but there is no particular problem as long as it is the same as the rotating shaft 2-2.

In other words, a material similar to ordinary stainless steel can be used.

In the present invention, the term "screw structure" refers to an integral combination of the screw 1-1 and the bridge portion 5-5, which is supported by a bearing or the like.

Furthermore, the term "end" does not mean the end, but rather refers to the part about 1/3 from the end of the entire length. The term "freely rotating relative to each other" refers to a state of relative motion, and of course one of the two may be stationary.

When the stirring rod according to the present invention is actually used for stirring work, the screw 1-1 is in a stationary state with respect to space.

The connecting portion between the bearing portion 4-4 and the screw 1-1 may be cylindrical, or may simply be bridged. Rather, a bridged structure is preferable.

The reason for this is that if the connecting part is cylindrical, the inside may become contaminated with liquid.

The degree of strength of the bridge part used to connect the bearing part 4-4 and the screw 1-1 varies depending on the degree of viscosity of the liquid to be stirred, the rotation speed, etc., but it is usually about the same as that of the rotating shaft. It is sufficient if the thickness is . The bearing portion 4-4 and the bridge portion may be connected by either a screwing method or an insertion method.

Next, the specific shape and size of the screw 1-1 will be described. The shape is a normal screw-like screw in appearance, but it is preferable that the rod from which the screw is formed has an edge in cross section.

This is because, as mentioned above, the purpose of using the screw set on the stirring rod as in the present invention is to constantly scrape out the highly viscous liquid that clings to the rotating shaft and rises.

It is sufficient to wind the screw portion 2 to 3 times. A suitable pitch is about 2 to 10 mm.

This is because if the pitch is too narrow, not only will processing be difficult, but also a highly viscous liquid will adhere to the screw portion during use, which will defeat the purpose of the present invention.

The conditions are the same regardless of the winding direction of the screw part 1-1, but the rotating direction of the stirring bar, i.e.
In the case of direct connection to the motor, it is necessary to match the rotation direction of the motor so that it has the following relationship.

That is, if a rotating stirring rod is viewed as a stationary body, it must relatively rotate in an apparent direction such that the screw portion is screwed toward the liquid at the bottom.

When actually using the stirrer, there is no problem because the motor connected to it can be rotated in either direction by changing the electrical connections. The cross-sectional area of the rod that forms the basis of the screw depends on the size of the stirring rod used, that is, the size of the rotating shaft, but in the case of a small rod for laboratory use, it is preferably about the same thickness as the rotating shaft.

In the case of a comparatively large one for industrial use, one with a cross-sectional area of about 1 to 10 cm ² is preferable.

Next, the depth of the liquid to be stirred in the container, the stirring speed, the viscosity of the liquid, the propeller It depends on the size, shape, etc., so it must be set according to the situation. Therefore, the bridge portion 5-5 must be structured so that it can be divided and assembled to change its length. The stirring rod equipped with the screw structure of the present invention can be used with propellers of various shapes as described above.

When the inner surface of the screw part and the outer surface of the rotating shaft rotate while sliding relative to each other, the narrower the gap between the sliding parts, the greater the scraping effect. I have to take care of it.

The bearing 4-4, which also serves as a holder for the rotating shaft 2-2, is used by being set in the opening of a container filled with liquid, but when it is necessary to isolate the target liquid from the outside air. It can be used by screwing it into a bearing with a mechanical seal function, which is prepared separately. In particular, if sealing is not required, the bearing 4-4 may be used by inserting it into a commonly used rubber plug or the like.

The method for creating the screw portion is not particularly limited, and is usually performed by cutting using a normal lathe.

[Brief explanation of the drawing]

Figure 1 is an external view of the stirring bar according to the present invention.
1 is a screw, 2-2 is a rotating shaft, 3-3 is a stirring blade, 4-4 is a bearing that also serves as a holder for the stirring blade, and 5-5 is a bridge that connects the screw and the bearing.

Claims (1)

[Scope of utility model claims] A structure that combines a screw structure disposed on the outer periphery of a rotating shaft, a rotating shaft that freely rotates with each other while in contact with the screw structure, and a stirring blade disposed at an end position of the rotating shaft. A stirring stick characterized by being equipped with.