Technology

Division of sound waves

Definition of untrasonics

Applicable fields of ultrasonics

• 1 The nature of sound wave

  Sound waves make the medium vibrate and just like water waves they do not remove the medium but energy can transmit through the medium

• 2 The velocity and wave length of sound waves

  v = fλ (v:velocity, f:frequency, λ:wave length)
  y = Asinω T(y:displacement)

• 3 The Modes of sound waves
  • Longitudinal wave
    

    The vibrating direction of a medium accords with transmitting one of wave vibration (Sound waves are invloved in longitudinal wave)

  • Latitudinal wave
    

    The vibrating direction of a medium shows right angle against the transmitting direction of wave vibration.

       

  • Fequency
    

    The number of periodic repetition of sound wave per second is in accordance with the reciprocal number of frequency. The unit is as Hz.

  • Period
    

    The time it takes to vibrate once is the same as the vibrating needs to travel the distance of wavelength. That is the reciprocal number of frequency.

  • Wave
    

    When the change of energy was brought about in the inner object owing to some shock.
    The energy transmitted gradually to the adjacent part of the object without making total removal of it. The object to which sound waves were trasmitted is called a medium. And the origianl source at which sound wave take place is called sound wave source.

  • Wavelength
    

    The length of intervals between waves or ridges of waves can be measured vertically against the surface of sound waves, when welocity indicates v, frequency f, the follwing formula can be determinded.

    

    • Frequency : As it vibrates twice a second : 2Hz
    • Period : As it is the reciprocal number of frequency, considering it as 1/2, Hz it is half a second.
    • Wavelength : Considering current speed is 3cm/sec, it can be substituted as
                      = vf
                      = 3 2
                      = 1.5cm
    • Ultrasonic cleaning
      :with low frequency generally indicates as 25.7KHz, Considering the current speed in the cleaning tank can be altered according to the temperature, it indicates 1483m at 20c, try to seek the wavelength.

• As more than two wave motions are overlapped, the followings aspects happened. The results of the wave motion are interference and likely to be determined originally by the period of wave motion, vibrating breath, aspects and the progressing direction on the surface of waves.
• Supplementary interference
  

  The aspects of two wave motions are so similar one another that the one floor is combined with thie other floor.

• Interference
  

  As the aspects of two wave motions are different, so the ridge is conflicted with one another.

• Standing wave
  

  As an example of interference the period, the vibrating breath and the progressing direction are in accordance with one another, the new aspects is apt to be occurred by the interference of other wave motions.

     

When the electric signal flowing from the ultrasonic generator is transmitted to the transducer of vibrating plate, the transducer turns the electric signal into mechanical one. The changed mechanical signal begins to resonate through the medium in the water, and accordingly the change of sound pressure happens to take on cavitation aspects. Through this processing the exfoliation and removal of a extraneous substance can be completed.
Such procedure aws stated above and can be defined as ultrasonic cleaning.

• Because of the side of ultrasonic decompression, sound pressure occurs one half periodically, cavitation increases in the liquid.
• The remarkably powerful pressure resulted from increased pressure one half periodically brings about repetition of contraction and expansion by turns.
• Such features as contraction implosion happen on account of the overwhelming pressure of the surface tension.
• A myriad of minute bubbles resulted from the contraction implosion can exfoliate and remove extraneous contaminants.

• Ultrasonic frequency
  

  Low frequency range is from 15KHz to 100KHz that is apt to occur caviation ranges.

• Oxidation
  

  Oxidation is the way in which ocidizing reaction can promote and ranges within approximately 300KHz.

• Surface tecsion
  

  The stronger the surface tension of the solution is, the higher the strength of cavitation becomes, but it decreases in number.

• The temperature of the water
  

  The higher the temperature is, the intensity of cavitation becomes, and on the other hand, the bubbles increase in number becomes.

• Viscosity
  

  The lower the viscosity is, the higher the intensity of cavitation

• Degassed water
  

  The lower the viscosity is, the higher the intensity of cavitation

• Erosion features
  

  The fact that the cleaning effect has been highly improved on account of ultrasonic cavitation features may be one of the most recognized benefits. On the other hand, erosion features as a by-product are likely to turn up. Therefore the cracks are apt to occur in the vibrating plate that is the source of the ultrasonics.

• The position of cleaning materials
  

  The fact that the posiitons between the oscillating plate and the material to be cleaned should be arranged in face to face with each other is considered to be beneficial. In case of multi-frequency, it is much more beneficial to be facing each other.

Accoustic steaming

As the ultrasonics transmits in the water, the difference of sound pressure influences on the medium. Because the different media have their own unique density, from the media which has higher pressure distribution than the others the ultrasound will be transmitted to the medium which hav lower pressure distribution. Therefore, the narrower the transmits area of ultrasound and the stronger the intensity is, the more effective the cleaning become. (The principle for the Horn ultrasonic cleaning)

Particle Accelerated velocity

Liquid particles keep on oscillating rapidly by way of the accelerated speed in proportion to the frequency square. And the semi-conductor and sub-micron of plane-plate molecule can be applied to removing extraneous substance.

y = AsinωT, a = d²y/dt² = -Aω²sinωT,
amax =Aω² = A(2πf)² : ( the accelerated velocity in proportion to the frequency square)

<Calculation for the accelerated velocity&rt;

I = ρcv² (v : oscillating velocity)
(I : Intensity of sound wave ρc : Acoustic impedance [pa.s/m])

(a :acceleration velocity, ω : radian frequency)

< The motion of liquid particles by way of accelerated velocity&rt;

Division of Sound Waves

• Pzt elemental : Crystal,Titanic acid barium,Zircon titanic acid
• Magnetic elemental : Nickel,Pelite series
• Langevin elemental :
  Metal electric poles are attached on the both sides of the piezo electricity or Pzt elemental,and then the elemental gets oscillate in resonance of frequency.
  As recently the fixed volt is generally used in the oscillator,it is called the BLT elemental.

The length of ultrasonic wave must be doubled integer number of wave length and attached for the ultrasound not to be pushed backward but to be pushed forward.icable fileds of Ultrasonic

The part where the initial machine shock has occurred then conectiong tween both poles with the positive pole and the negative one by making use of the pzt elemental.

Alternating surrent signal plate Generally to input the resonance frequency of the elemental

To be cut and attacked as half wave legth of the integer number
Material : aluminium
Purpose : Amplitude the miniute vibrating

• If we give the vibration corresponding to 40KHz to the regular hexahedron of the "Horn" attached with two oscillators, the "Horn" perhaps may produce the equivalent of complex resonance ranging from 40KHz to 90KHz.
• There are two kinds of multi-frequency. One is 28 KHz, and the other is 40 KHz.
• This item (mullti-frequency) may be somehow weak in cleaning effect in comparison to mono-frequency, but it does not have the trouble relating to standing wave,therefore, it is much beneficial for the materials to be cleaned evenly.
• The declining phase of the electric power owing to the water-level and flowing in the whirls is not remarkable but slight. Not only the life of the oscillators is long, but it is also very easy to maintain and repair the equimspment.