JPH06254371A - Overhang type agitation shaft for high speed rotation - Google Patents

Abstract

PURPOSE:To provide an overhang type agitation shaft with a long shaft enabling to uniformly and perfectly mix or disperse a high viscous substance at a high speed, in agitation of the high viscous substance, etc., having a high resistance value against its rotational torque. CONSTITUTION:A shaft size of the overhang type agitation shaft which is supported rotatably at one side 2a of a shaft body 2, being made to a non- supported state at the other side 2b and is attached with an agitation blade 3, etc., is formed so that it becomes gradually smaller sizes from side 2a being supported rotatably toward the other side 26 in a non-supporting state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overhang type stirring shaft which is suitable for uniformly and completely mixing or dispersing a highly viscous substance having a high resistance against a rotating torque at high speed.

[0002]

2. Description of the Related Art Conventionally, various industries such as the dissolution of pigments and varnishes in the paint industry, the dispersion and emulsification of pigments and oils in the ink industry, and the dispersion of fine powders such as carbon and ceramics in the inorganic fine powder industry have been used. Attempts are being made to manufacture new substances having excellent properties by uniformly stirring different materials and by thoroughly mixing or dispersing them.

In the production of such a new substance, it is necessary to uniformly and completely mix or disperse different materials.
For that purpose, an excellent stirring device having a high torque stirring force by high speed rotation is required.

However, a general stirring shaft in this type of device is a vertical rotary type in which the shaft has the same shaft diameter and the upper and lower sides of the shaft are rotatably supported by the device, or the shaft has the same shaft diameter. In addition, an overhang type rotary type in which one side of the shaft is rotatably supported by the device and the other side is in a non-axially supported state is used.

As the stirring shaft (long shaft) of a large-sized, high-speed device, the above-mentioned vertical rotary type is generally used. When the overhang type rotary type is rotated at a high speed, it causes a violent resonance phenomenon during rotation and causes shaft damage, so it is often used for low speed rotation and only when the shaft length is extremely short. It is only used for high speed rotation.

By the way, the rotating stirring shaft has a torsional moment for transmitting rotational power during its rotation.
It receives bending moment due to the resistance imbalance of the stirring fluid, the shape and weight imbalance of the stirring blade, and axial thrust load due to the inclined blade.

In the vertical rotary type, since the upper and lower sides of the shaft body are axially supported by the device due to its structure, when used as a stirring shaft for low speed rotation, the twisting moment and bending moment of Since there are few troubles related to axial force and the stress calculation formula has been sufficiently clarified, there are few problems in design, and it can be used as a stirring shaft for low speed rotation without any problems.

However, since the structure of the overhang type rotary type is rotatably supported by the device only on one side of the shaft body and the other side is in the non-axially supported state as described above. As the number of rotations is increased, the resistance of the stirring material to rotation (liquid resistance etc.) increases, and stirring vibration occurs due to the shape and weight imbalance of the stirring blades. Since the shaft body provided with the blade has its own vibration range, when the stirring frequency approaches the vibration range, a so-called "resonance phenomenon" occurs.

However, if the time width of occurrence of this resonance phenomenon can be passed within a time period in which the shaft is not destroyed, that is, within the range in which the elastic strength of the shaft can be maintained, the resonance phenomenon is subdued, and thereafter the above-mentioned stirring vibration range. Just becomes a problem,
If the stirring shaft rotates within this stirring vibration range, problems such as shaft damage will not be a concern.

However, in particular, when high-speed stirring for stirring a highly viscous liquid, mixing and dissolving a solid and a liquid, or dispersing a fine powder is carried out using an overhang type stirring shaft having the same diameter, Due to the large resistance vegetation on the stirring shaft and the stirring blade, it takes several seconds for the passage time of the resonance phenomenon occurrence time and it cannot pass in a short time. A shaft breakage occurs because the elastic strength can easily be exceeded.

[0011]

As described above, when the resistance value against agitation is large, the shaft vibration phenomenon due to the bending of the shaft and the left-right turning cycle of the shaft determined by the rigidity of the shaft and its various conditions are used. A "resonance phenomenon" occurs when it matches the vibration that occurs during rotation, but this is called the critical speed in the sense that it becomes a critical area because the vibration is amplified and shaft destruction occurs.

The shaft breakage due to this dangerous speed changes from small vibration to severe vibration, causing permanent bending strain of the shaft, fatigue breakage, breakage of the shaft seal part, breakage of the bearing part, breakage of the transmission mechanism, and the like. There are many other factors that can affect the critical speed, and the critical speed does not match the actual critical speed even when calculated from the currently used trial calculation formula. For this reason, in a normal case, the designer is designing so that the critical speed value obtained by the trial calculation formula currently used is 30 to 40% or more higher than the actual rotational speed in use. Is.

Of course, there is an overhang type stirring shaft which is still used for high speed rotation of 800 to 1500 RPM, but this is a case where the shaft length is short and low torque is required. That is, the shaft diameter may be thin, permanent strain due to that is unlikely to occur, and some homogenizers that can pass through this while the critical speed range becomes low and liquid resistance is small, and the shaft length is also extremely short. Medium-speed / high-torque machine (600-800RP)
High torque machines using an overhang type stirring shaft, which is used only for M) and is generally known at present, is said to be impossible at a rotation of about 10 to 400 RPM.

Due to the above-mentioned background, the overhang type stirring shaft does not have a lower steady rest like the vertical type stirring shaft due to its structure, and the upper rotation supporting mechanism does not become complicated and large.
Although it has an advantage that it can be formed comparatively compactly, it has a problem that it cannot be used for long-axis and high-speed rotation because of the reason described above. We have conducted diligent research to solve the problem.

The present invention has been made in view of the above circumstances, and an object thereof is to agitate a highly viscous substance having a high resistance value against a rotating torque and to uniformly mix it at a high speed. Alternatively, it is to provide a long-axis overhang type stirring shaft which can be dispersed.

[0016]

In order to achieve the above-mentioned object, the present invention is, as described in claim 1, rotatably supported on one side of a shaft and non-axial on the other side. In the overhang type stirring shaft in which the stirring blade is mounted while being supported, the diameter of the shaft body is
It is characterized in that the diameter is gradually reduced from one side that is rotatably supported to the other side that is not supported.

Further, as described in claim 2, the shaft body is formed in a taper shape from one side to the other side, and the shaft diameter is gradually reduced, and further as described in claim 3. The shaft body is formed as a multi-stage different diameter stirring shaft in which the shaft diameter gradually decreases from one side to the other side via a step portion.

[0018]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is an explanatory view showing an example of a stirring device,
As shown in FIG. 2, one side 2a of the shaft body is provided in the apparatus main body 1.
In the above, the other side 2b is rotatably supported, and the other side 2b is not supported, and the shaft body is tapered from one side 2a to the other side 2b so that the shaft diameter is gradually reduced. An overhang type stirring shaft 2 is attached.

The wall structure of the device, the bearing portion, the shaft sealing portion,
The drive motor and the like can be constituted by conventionally known means, and since they are not directly related to the gist of the present invention, detailed description thereof will be omitted.

Next, a description will be given based on a specific example.
As shown in FIG. 5A, the stirring shaft 2 has an axial length of 850 mm from the one side 2a rotatably supported by the apparatus body 1 toward the other side 2b, and Diameter is 1
Upper side 21 formed with the same diameter of 00 mm (Φ100)
And extends from this upper part 21 and has a length of 3100 mm
And a tapered lower side 22 whose diameter gradually decreases toward the other side 2b in the non-axially supported state from Φ100 to Φ50. A stirring blade 3 of Φ500 is attached to the end of the lower side 22.

The operation and the like of the stirring shaft 2 will be described below. In order to clarify the function and effect, the stirring shaft 2 is formed to have the same length as the tapered stirring shaft 2, and the diameter thereof is from the upper side. Formed up to the lower side with the same diameter of Φ100, that is, forming a stirring shaft of a conventional stirring shaft structure (see FIG. 4 (a), hereinafter referred to as a conventional shaft),
An explanation will be given based on comparison data with this conventional axis.

The liquid used for stirring the sample is a mixed liquid for the purpose of dissolving water and the pigment and the varnish (hereinafter referred to as a used liquid). In addition, the stirring environment is in a melting pot with a throughput of 8000 l.
Liquid viscosity; 1000 CP, pressure; atmospheric pressure, temperature; 80 ° C.,
The number of rotations was stirred under the condition of 1200 RPM.
The required power was set to 60H based on the results of various experiments and the strength of each part was examined. The critical speed range was Nc = 400.
Estimated as a range of ~ 450 RPM.

Test Example 1 First, the conventional shaft was stirred in water. In this case, vibration occurred in the critical speed range (650 to 700 RPM), but reached the use rotation without expanding to the inoperable state. However, since the vibration does not stop, it cannot withstand long-term operation, and it was impossible to use it as a stirring machine.

Test Example 2 Next, the conventional shaft was agitated in the working liquid. In this case, when the critical speed range (650 to 700 RPM) is reached, violent vibration is generated in the shaft, which causes the vibration of the melting tank to become the vibration of the entire support frame, which results in abnormal vibration noise and violent vibration of the whole. Became impossible. When the conventional shaft was examined after the operation was stopped, breakage of the bearing portion and breakage of the shaft sealing portion were recognized, and the shaft body was bent up to 17 mm in the inter-axis portion and 67 mm in the intermediate portion, and twisting was also generated.

This is because in a low viscosity such as water used in Test Example 1, there is a difference in the followability of changes in the rotational speed of the rotary blade and changes in the vortex flow of the liquid, and the shaft has a liquid resistance. Since the passage time is small and the passage time in the critical speed range is short, the resonance can pass without expanding, and it is considered that only the influence of the shaft contact during use rotation was not absorbed and vibration did not stop.

However, since the liquid resistance is large in the high viscosity as in Test Example 2, the increase in the rotational speed of the rotary blade and the increase in the eddy current of the liquid approximately follow each other, and it takes time to increase the rotational speed. Since the passing time of the critical speed range cannot be smoothly passed in a short time, and it passes slowly in this band, the agitation frequency and the natural frequency easily coincide with each other, causing resonance. It is considered that the shaft runout was amplified and permanent bending strain of the shaft was generated.

Test Example 3 The tapered stirrer shaft 2 according to the example was stirred in the working liquid in the same manner as in Test Example 2 above. In this case, as in the case of stirring in water in Test Example 1 above, the critical speed range (650 to 700 RPM) was also passed smoothly to reach the rotation speed of 1200 RPM, and long-term operation in this rotation state was performed. There were no problems with the conventional shaft, such as shaft damage.

The reason will be described below with reference to FIGS. 4 (a) and (b) and FIGS. 5 (a) and 5 (b). In this case, the bending moment is represented by M and the deflection is represented by δ. When the rotor blade weight W ₁ = 10.5 kg and the overhang portion shaft weight W ₂ = 192 kg, the trial calculation formula for the conventional shaft is as follows.

[0029]

[Formula 1] M = W ₁ L + W ₂ L / 2 = 10.5 × 3.1 + 192 × 3.1 / 2 = 330.15 kg · m

[0030]

[Equation 2] ^{_{δ = W 1 L 3 / 3EL}} + W 2 L 3 / 3EL ^{[E = 2.1 × 10 6 kg /} cm 2 ] ^{[I = π × 10 4/64} = 490c m 4 ] [delta] = 10 ⁶ × 490 + 192 × 310 ³ /8×2.1×10 ⁶ +490 = 0.796 cm

Next, each trial calculation formula for the tapered stirring shaft 2 according to the embodiment will be shown. The rotor blade weight W ₁ ; 7.1k
g, shaft weight of overhang part W ₂ = 47.8 kg (Φ5
0) and the shaft weight W ₃ = 63.7 kg (Φ50).

[0032]

Formula 4 M = W ₁ L + W ₂ L / 2 + W ₃ L / 3 = 7.2 × 3.1 + 47.8 × 3.1 / 2 + 63.7 × 3.1 / 3 = 162.24 kg · m

[0033]

[Equation 5] _{^{δ = W 1 L 3 / 3EL}} + W 2 L 3 / 8EL + W 3 L 3 / 15EL ^{[E = 2.1 × 10 6 · kg} / cm 2 ] ^{[I = π × 10 4/64} = 490 cm 4 ] ^{δ = 7.2 × 310 3 /3×2.1×10 6} × 490 + 47.8 × 310 3/8 × 2.1 × 10 6 × 490 + 63.7 × 310 3 /15×2.1×10 6 × 4 90 = 0.366 cm

As is clear from the above calculation results, the bending moment M and the bending amount δ of the Taber-shaped stirring shaft according to the embodiment are both 1 in comparison with the conventional stirring shaft having the same diameter. It turns out that it is / 2. Moreover, it is confirmed by calculation and actual experimental results that the tapered stirrer shaft can maintain sufficient rigidity even when examining each stress such as the torsional moment and the axial thrust load.

In addition, due to the small diameter portion of the tapered stirring shaft, the mounting boss of the stirring blade may be smaller than that of the conventional stirring shaft, and the weight of the mounting boss can be reduced. The reduction of the weight leads to a reduction in the amount of shaft deflection, that is, a reduction in runout. Further, as the shaft diameter gradually changes to a small diameter, the vibration of the lower stirring blade is absorbed in the process of being transmitted to the upper portion, and resonance is prevented.

The reason why the tapered stirring shaft has such a good result as a countermeasure against the dangerous speed is that the theory will be further clarified and the proof will be given at a later date. The overhang type stirring shaft according to (1) solves various problems of the conventional overhang type stirring shaft in which the diameter of the shaft is formed to have the same diameter in the longitudinal direction.

Next, referring to FIG.
As described above, the tapered stirring shaft 2 has been described, but as shown in FIG.
The stirring shaft 4 may be formed by the multi-stage different diameter shafts 42a to 42d whose shaft diameter gradually decreases via 42d1. In this case, the tapered stirring shaft 2
The same effects as are obtained with each step 42a1-4a
Since the stirring blades 3 ... Are easily attached in 2d1, a plurality of stirring blades can be arranged in multiple stages in the vertical direction of the shaft, and a stirring shaft and a stirring device with higher torque can be obtained.

[0038]

As described above, in the stirring shaft according to the present invention, the diameter of the shaft body is gradually reduced from one side rotatably supported to the other side in the non-axially supported state. Since it is configured as a multi-stage different diameter stirring shaft that has a taper shape or a small diameter through a step, the vibration of the lower rotor blade is absorbed by the shaft diameter that gradually changes to a small diameter to prevent resonance. Therefore, it is possible to provide a long-axis overhang type stirring shaft capable of uniformly mixing or dispersing a highly viscous substance having a high resistance value against a rotating torque uniformly at high speed without causing shaft breakage.

Therefore, it is possible to provide a high-torque agitating device for different materials in various industries, and it is possible to promote industrial promotion in the field of this type of technology.

[Brief description of drawings]

FIG. 1 is an explanatory view of a stirring device using a stirring shaft according to the present invention.

FIG. 2 is a diagram showing a first embodiment of a stirring shaft according to the present invention.

FIG. 3 is a diagram showing a second embodiment of the stirring shaft according to the present invention.

FIG. 4 is an explanatory view showing an example of a conventional shaft and trial calculation of a bending moment and a bending amount thereof.

FIG. 5 is an explanatory diagram showing an example of a stirring shaft according to the present invention and a trial calculation of a bending moment and a bending amount thereof.

[Explanation of symbols]

 1 Device body 2 Tapered stirring shaft 3 Stirring blade 4 Multi-stage different diameter stirring shaft

Claims (3)

[Claims] 1. An overhang type stirring shaft in which one side is rotatably supported and the other side is in a non-axially supported state, and stirring blades and the like are mounted, wherein the shaft body is An overhang type stirring shaft for high-speed rotation, wherein the diameter is gradually reduced from one side rotatably supported to the other side in a non-axially supported state. 2. The overhang type stirring shaft for high speed rotation according to claim 1, wherein the shaft body is tapered from one side to the other side, and the shaft diameter is gradually reduced. 3. The high-speed rotation according to claim 1, wherein the shaft body is formed as a multi-stage different diameter stirring shaft in which the shaft diameter gradually decreases from one side to the other side through a step portion. Overhang type stirring shaft for.