JPH11235523A - Low frequency vibration agitating vessel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low frequency vibration agitating vessel which is not resonated by operating frequency of a low frequency vibration agitator and excels in vibration proofing and has improved durability. SOLUTION: This low frequency vibration agitating vessel is constituted of a flat plate 1 and a reinforcing frame 2. A fundamental frequency fn of an arbitrary region of the flat plate 1 constituting the low frequency vibration agitating vessel exceeds two times an agitation low frequency f0 of the low frequency vibration agitating vessel. The fundamental frequency fn of an arbitrary region of the flat plate 1 is not less than 120 Hz and an agitation low frequency f0 of the low frequency vibration agitating vessel is 30-60 Hz.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-frequency vibration stirring tank having excellent vibration isolation.

[0002]

2. Description of the Related Art A low-frequency vibration stirrer has a structure in which a vibration motor and a stirring blade are connected via one or a plurality of vibration shafts. The liquid is transmitted to the vibrating blade to flow and agitate the liquid in the tank. The agitation by this method can perform uniform and sufficient agitation with low power consumption as compared with the method of rotating the agitation blade, so that the manufacturing process of chemical products such as paints, chemical products, foods, chemicals, etc. It is widely used in fields such as pretreatment, degreasing, and plating.

[0003] Such a low-frequency vibration stirring tank is usually composed of a thin plate and a reinforcing frame. However,
When the low frequency vibration stirrer is operated, vibration energy is transmitted to the low frequency vibration stirrer itself, and the tank itself vibrates, causing fatigue deterioration of the tank and piping system, and it is difficult to ensure sufficient durability. there were. Further, in particular, when the tank itself causes resonance, there is a possibility that a destructive action may be exerted.

[0004]

SUMMARY OF THE INVENTION In view of the above, the present invention provides a low frequency vibration stirrer which has excellent vibration isolation and improved durability without resonating with the operating frequency of the low frequency vibration stirrer. The purpose is to do so.

[0005]

SUMMARY OF THE INVENTION The present invention is a low-frequency vibrating agitation tank composed of a flat plate and a reinforcing frame, wherein a fundamental frequency of an arbitrary portion of the flat plate constituting the low-frequency vibrating agitation tank is provided. f _n is the low frequency oscillation stirred tank in which more than 2 times the agitating low-frequency frequency f ₀ of the low frequency vibration stirring vessel. In this specification, the fundamental frequency refers to a natural frequency having the smallest frequency. Hereinafter, the present invention will be described in detail.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION A low-frequency vibration stirring tank of the present invention typically comprises a flat plate 1 forming a tank and a reinforcing frame 2 fixed to the flat plate 1, as shown in FIG. I have. The object to be treated is introduced into the tank from the tank entrance 3, and after being processed, exits from the tank 4 out of the tank. A low frequency vibration stirrer (not shown) is provided in the low frequency vibration stirrer. Further, a pipe may be installed in the low-frequency vibration stirring tank. The reinforcing frames 2 are usually installed in a grid pattern at regular intervals, but it goes without saying that the present invention is not limited to this.

In FIG. 1, the flat plate 1 is composed of a plurality of regions separated by the reinforcing frame 2 by a rectangle having two sides A and B adjacent to each other. Since the flat plate 1 is fixed by the reinforcing frame 2, the fundamental frequency of an arbitrary portion thereof is substantially the fundamental frequency of a rectangular flat plate having two sides of A and B adjacent to each other. Can be considered to be. Fundamental frequency f of any rectangular area of the flat plate
_n can be calculated by the following equation (1).

[0008]

(Equation 1)

However, ω _n = 2πf _n . Equation (1)
In the _equation , √ (E _g / γ) represents the speed of sound inside the flat plate material, and is 5.12 × 10 ⁵ cm / s in the case of a steel material. ν represents the Poisson's ratio of a flat material, and in the case of steel, 0.28 to 0.3
It is. A and B represent the span (cm) of the reinforcing frame.
t represents the thickness (cm) of the flat plate.

In the present invention, the above f _n = ω _n / 2π
Is more than twice the stirring low frequency vibration frequency f ₀ of the low frequency vibration stirring tank. If it is less than twice, the vibration stress of the low-frequency vibration stirring tank due to the applied vibration force becomes too large, and it is not possible to secure a sufficient vibration-proofing property.

The above-mentioned low frequency vibration stirring frequency f ₀ is the frequency of the low frequency vibration stirring device installed in the low frequency vibration stirring tank. In the present invention, there is no need to particularly consider harmonic frequencies exceeding twice the stirring frequency f ₀ . This is because, as shown below, the energy of the third and higher harmonics is sufficiently smaller than the vibration energy of the fundamental frequency,
This is because it does not particularly affect the durability of the low-frequency vibration stirring tank.

That is, as shown in FIG. 2, in the frequency analysis of the vibration energy transmitted to the vibration stirring tank by the low frequency vibration stirring, the component of the inverter frequency is the dominant frequency, and the energy of the harmonic is the energy of the inverter frequency. It is about 1/100 (about 40 dB smaller). Of these, 2
Although the energy of the next harmonic (double frequency) is relatively large, the vibration energy of the third or higher harmonic component is
It can be ignored in considering anti-vibration measures.

Therefore, it can be seen that if the resonance with a frequency component of twice or less the stirring frequency f ₀ can be prevented, sufficient vibration isolation can be ensured. That is,
In addition to preventing resonance with f ₀ , a sufficient safety factor can be ensured to prevent the second harmonic from resonating with the fundamental frequency of the flat plate constituting the stirring tank. In this way, at least the fundamental frequency f _n of any part of the flat plate constituting the low frequency vibration stirring tank exceeds twice the low frequency vibration f ₀ of the low frequency vibration stirring tank. The fact that it is possible to exhibit sufficient practical vibration-proofing properties by designing such a structure is the basis of the present invention.

The stirring frequency f _o of the low frequency vibration stirrer is
Usually, it is 30-60 Hz. Therefore, in the present invention, it is preferable that f _n exceeds 120 Hz (ω _n = 754 rad / s).

In designing the low-frequency vibrating stirring tank of the present invention, it is necessary to consider mechanically sufficient strength in consideration of stress acting on each part of the tank by vibration energy. The vibration force applied from the low-frequency vibration stirrer and the water pressure in the tank in the tank composed of the flat plate and the reinforcing frame material can be calculated according to the thickness of the reinforcing frame material. In the case where the thickness is smaller than the thickness of the flat plate, a calculation using a model shown in FIG. 3 which assumes that an evenly distributed load acts on the flat plate 1 supporting the periphery can be applied. Further, when the thickness of the reinforcing frame member is thicker than the thickness of the flat plate, a calculation using a model shown in FIG. 4 which assumes that an evenly distributed load acts on the flat plate 1 having a fixed periphery is applied. be able to. The span A of the reinforcing frame
3 and FIG. 4 may employ 2a and 2b, respectively.

In general, when a load of qkgf / cm ² acts on a rectangle having a thickness t, a long side 2a and a short side 2b, the maximum stress σ _max in the short side direction at the center of the flat plate is σ _max = αqb ² / t Represented by ² . In the formula, α is a value determined according to the value of a / b in accordance with the two models described above. For example, α is a value of a model that is assumed to have an evenly distributed load acting on a flat plate supporting the periphery. In this case, if a / b = 1.000, α
= 1.150, and in the case of a model in which an evenly distributed load acts on a flat plate having a fixed periphery, a / b = 1.
If it is 000, α = 1.231. As the spans A and B of the vibration frame, 2a and 2b may be used in the models of FIGS. 3 and 4, respectively.

The magnitude of the allowable stress at any part of the low-frequency vibration stirring tank differs depending on the material constituting the low-frequency vibration stirring tank. As the material, generally, a steel material is often used, but the material is not limited thereto, and may be plastic, various alloys, non-ferrous metals, or the like. For example, when using a steel material, assuming that the external vibration force applied from the low-frequency vibration stirrer is 0.05 kg / cm ² , the magnitude of the allowable stress at any part of the low-frequency vibration stirring tank with respect to the external vibration force is as follows: 200kg considering safety factor
/ Cm ² is preferably set. That is, in the low-frequency vibration stirrer of the present invention, the vibration stress at an arbitrary portion of the tank is such that the external vibration force applied from the low-frequency vibration stirrer is 0.
Even 05kg / cm ^2, which is preferably configured to be 200 kg / cm ² or less.

The low-frequency vibrating agitation tank is usually provided with a pipe, and it is preferable that the pipe is also designed so that the stress caused by the vibrating force is not excessive. Since the above-mentioned piping is usually installed in the tank main body by a fitting, the stress caused by the excitation force can be calculated by applying a model regarded as a both-ends supporting beam. For example, the frequency of the excitation force is 43 Hz, the pipe is a stainless steel pipe for piping, the support length is 80 cm, and the outer diameter of the pipe is 4 mm.
Assuming that the thickness is 2.7 mm and the thickness is 3.6 mm, the second moment of area I of the hollow cylinder is I = (π / 64) × (D ⁴ −
d ⁴ ) [where D represents the outer diameter and d represents the inner diameter], the spring constant k = 48 EI / l ³ [where E represents the Young's modulus and 1 represents the supporting length. ], Fundamental frequency ω ² = k
/0.5m, where m represents the mass of the pipe of the supported length, k = 1677.
8 kgf / cm and ω ² = 11786699.5. Since the piping system generally constitutes a very complicated vibration system, it is often difficult to estimate the exciting force acting on the pipe itself. However, by assuming that the external vibration force applied from the low-frequency vibration stirrer is a vibration force acting on the pipe, the maximum amplitude of the pipe, that is, the maximum deflection can be calculated. The stress due to the excitation force can be obtained from the maximum deflection.

In the low-frequency vibration stirrer of the present invention, the fundamental frequency of each part is different from the frequency of the external vibration force applied from the low-frequency vibration stirrer by more than twice in all parts. The low-frequency vibration stirring tank does not resonate,
The manufacturing process of chemical products such as paints, chemical products, foods, pharmaceuticals,
It can be suitably used as an immersion tank used for pretreatment, degreasing, plating and the like of an automobile body.

[0020]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 An external vibration force of 0.05 kg / cm ² , a vibration frequency of 42 Hz, a steel plate (Poisson's ratio ν = 0.3, Young's modulus E = 21000 kg / mm ² , size 55 cm × 50 c)
The basic frequency and the vibration stress due to the external vibration force were determined for 17 sheets whose thickness in m) was increased by 0.5 mm in the range of 1.0 to 9.0 mm. The results are shown in FIG.
In the figure, the data points are for the case where the left end point has a plate thickness of 1.0 mm.
Is the case. From this result, the allowable stress was set to 200 kg /
If cm ^2, and the number of fundamental vibration, is set to more than 86Hz to greater than 2 times the frequency of the external vibration force, it can be seen that the stresses within the allowable range in each part of the bath.

Next, a low-frequency vibration stirring tank having the structure shown in FIG. 1 was prepared. The material used is a steel plate (Poisson's ratio ν = 0.
3, Young's modulus E = 21000 kg / mm ² ), and the thickness of the reinforcing frame material was smaller than the thickness of the flat plate. The span of the reinforcing material was A = 55 cm, B = 50 cm, and the thickness of the steel plate was 5.0 mm. The fundamental frequency of the flat plate constituting the tank is 89.2 Hz. External vibration force applied from low frequency vibration stirrer is 0.05kg / c
m ² , and the vibration frequency was 43 Hz, the vibration stress due to the external vibration force was 167.2 kg / cm ² .

From the above, if the basic frequency of the flat plate exceeds twice the frequency of the external vibration force applied from the low frequency vibration stirrer, the vibration stress due to the external vibration force is reduced. It was less than the allowable stress, and it was found that a sufficient vibration-proof effect could be obtained. Therefore, the thickness of the plate and the length of the side of the reinforcing member are determined so that the fundamental frequency of the flat plate exceeds twice the frequency of the external vibration force applied from the low-frequency vibration stirrer. It was found that the vibration can be controlled.

[0024]

According to the present invention, the fundamental frequency of each part of the low-frequency vibration stirrer differs more than twice as much as the frequency of the external vibration force applied from the low-frequency vibration stirrer. Therefore, a low-frequency vibration stirring tank having extremely excellent vibration isolation can be manufactured without causing resonance of the low-frequency vibration stirring tank, and therefore, a low-frequency vibration stirring tank with improved durability is provided. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing a configuration of a low-frequency vibration stirring tank of the present invention.

FIG. 2 is a vibration energy spectrum of a low frequency vibration stirrer installed in a low frequency vibration stir tank.

FIG. 3 is a conceptual diagram of a rectangular plate supporting the periphery and receiving an evenly distributed load qkgf / cm ² .

FIG. 4 is a conceptual diagram of a rectangular plate having its periphery fixed and receiving an evenly distributed load qkgf / cm ² .

FIG. 5 is a graph showing changes in fundamental frequency and vibration stress when the plate thickness is changed in Example 1. The vertical axis is
Vibration stress (kg / cm ² ), and the horizontal axis represents the fundamental frequency (Hz).

[Description of sign]

DESCRIPTION OF SYMBOLS 1 Flat plate 2 Reinforcement frame 3 Entry part 4 Departure part A, B Span of reinforcement frame 2a, 2b Length of side of model rectangular plate which receives uniform load

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Seiichiro Shirahata 19-17 Ikedanakacho, Neyagawa-shi, Osaka Nippon Paint Co., Ltd. (72) Inventor Tamotsu Soda 19-17 Ikedananakacho, Neyagawa-shi, Osaka Nippon Int Co., Ltd.

Claims (2)

[Claims] 1. A low-frequency vibration stirrer comprising a flat plate and a reinforcing frame, wherein the fundamental frequency f _n of an arbitrary portion of the flat plate constituting the low-frequency vibration stirrer is such that the low-frequency vibration stirrer A low-frequency vibration stirring tank characterized in that the frequency exceeds twice the stirring low-frequency frequency f ₀ of the stirring tank. 2. The basic frequency f _n of an arbitrary portion of a flat plate is 1
And at 20Hz or more, the low-frequency vibration stirring vessel according to claim 1, wherein agitation of the low frequency vibration stirring tank low frequency frequency f _o is 30 Hz to 60 Hz.