DE19811266C1 - Method of cleaning filter frames - Google Patents

Abstract

The method of cleaning filter screens uses ultrasound with the screen frame longitudinally oscillated. The frame (1) can be cleaned through a coupling (2) which supports the cleaning axis (5) of the oscillating system (4) in the plane of the frame which transfers the oscillation.

Description

The invention relates to a method for exciting a Screen frame with ultrasound according to the preamble of Claim 1.

It is common knowledge to sieve to use different goods ultrasound. The vibrating movements generated by the ultrasound are transferred to the screen surface and practice one favorable influence on the sieve throughput and the material to be sieved out. The vibrations transferred to the screenings cause a reduction in surface tension and the agglomeration forces, so that a clogging of the Sieve mesh is largely prevented.

The known ultrasound Screening devices and screening processes exist in essentially from a sieve frame with a applied screen surface and one on the screen frame coupled via an ultrasonic transducer Ultrasound source, the transducer being the high frequency  electrical vibrations in mechanical Converts bending vibrations.

In WO 94/27748 a device and a Methods for screening, classifying, sifting, filtering or Sorting fabrics with in a sieve frame provided screen area and assigned Ultrasonic transducer through which the screen surface Vibrations are lead described.

The ultrasonic transducer is one of the screen surfaces adjacent resonator assigned to the resonance of the ultrasonic transducer and tuned in by the latter Bending vibrations are displaceable. The one from the transducer generated longitudinal vibrations are in the tangential to the longitudinal direction of vibration arranged resonator bars in bending vibrations of the transformed at the same frequency.

A disadvantage of all known embodiments is that from the oscillation principle "bending vibrator" resulting large dimensions are not sufficient enable compact design of the screening device.

The object of the invention is a method for excitation of screen frames using ultrasound which is a more compact design of screening devices than previously known is guaranteed.

The solution to this problem results from the features of claim 1. Appropriate configurations of Invention are specified in the subclaims.  

The excitation of a screen frame with ultrasound as Longitudinal transducer ensures a flatter and therefore more compact design of sieve frames than after Bending vibrator principle excited screening devices.

In particular by attaching the vibrating Systems to the element to be excited with the vibrations (e.g. sieve frame) with a lateral offset a compact design can be achieved in that the vibrating system is placed under the sieve frame becomes. It is also the formation of ring shapes (also elliptical shapes) possible for the sieve frame, especially if by a coupling element Excitation axis of the vibrating system in the plane of the screen frame transmitting the vibrations is shifted.

The invention is in one Embodiment of an annular sieve frame explained in more detail. In the single figure is in one schematic representation of the annular sieve frame represented with the ultrasound source.

As shown in the figure, a circular sieve frame 1 is formed from an integral multiple of λ / 2 elements, one of the λ / 2 elements being formed by a coupling element 2 .

The coupling element 2 consists of two λ / 2 longitudinal transducers 3 , which are interconnected in their maximum amplitude.

An ultrasound generating system 4 (ultrasound transducer) is attached as a λ / 2 longitudinal oscillator to the lower λ / 2 longitudinal oscillator 3 of the coupling element 2 .

The high-frequency mechanical longitudinal vibrations generated by the ultrasonic transducer 4 are transmitted via the coupling element 2 to a sieve frame 1 , propagate over the entire circumference in accordance with diagram II of the figure and are transmitted uniformly to the sieve fabric (not shown).

In the case of large screen areas, it may be expedient to arrange a plurality of circular, elliptical or rod-shaped screen frames 1 , depending on the geometry of the screen area, under the screen area in order to ensure an effective screen function.

Diagram I of the figure shows the course of the oscillation in converter 4 and in coupling element 2 . Diagram II shows the course of oscillation in the sieve frame 1 , the amplitude quantity a being plotted over the oscillation location x in both diagrams I, II of the figure. There is a vibration node at location x ₀ .

Due to the longitudinal vibrations of the system 4 , a sieve applied to the sieve frame 1 is set into lateral movements which largely correspond to the sieve movements during manual sieving. Compared to the known screening devices according to the prior art, the excitation of the screening surface is offset by 90 °.

The invention is not limited to that described here Embodiments limited. Rather, it is possible by combining the features more Realize embodiments without the frame to leave the invention. So it is also an advantage conceivable a longitudinal oscillation movement after the Invention with a bending vibrator movement known Way to combine on a sieve frame.

Reference list

1

system to be vibrated (sieve frame)

2nd

Coupling element

3rd

λ / 2 longitudinal transducer

4th

vibrating system

5

Excitation axis of

4th

6

Axis of

1

aAmplitude
xlocation
x ₀

place

Claims (6)

1. A method for exciting a screen frame with ultrasound, characterized in that the screen frame ( 1 ) is excited as a longitudinal oscillator. 2. The method according to claim 1, characterized in that the screen frame ( 1 ) via a coupling element ( 2 ) is excited, which the excitation axis ( 5 ) of the vibrating system ( 4 ) in the plane ( 6 ) of the vibrating screen frame ( 1 ) shifted. 3. The method according to claim 2, characterized in that the coupling element ( 2 ) is formed from at least two longitudinal oscillators ( 3 ) coupled in their amplitude maximum. 4. Process according to claims 1 to 3, characterized in that the screen frame ( 1 ) which transmits the vibrations is formed in a ring from an even number multiple of λ / 2 elements, one of the λ / 2- already being formed by the coupling element ( 2 ). Elements is formed. 5. The method according to claims 1 to 3, characterized in that the vibrating screen frame ( 1 ) is rod-shaped. 6. The method according to claims 1 to 5, characterized in that a plurality of annular, elliptical and / or rod-shaped, the vibration-transmitting screen frame ( 1 ) are arranged under a screen ( 1 ).