JP6011220B2 - Powder sieving apparatus and powder sieving method - Google Patents

Description

  The present invention relates to a powder sieving apparatus and a powder sieving method for classifying powder using a sieve.

  In a steelmaking line in an ironmaking plant, impurities such as sulfide, phosphorus and carbon in hot metal are taken into slag by a chemical reaction to produce high purity molten steel. Among them, in the desulfurization process, a method called the KR (Kanbara Reactor) method is used in which a desulfurizing agent mainly composed of calcium oxide is added to a ladle containing molten iron, stirred with a blade made of refractory, and the sulfide is removed. Generally adopted. The desulfurization slag produced in the desulfurization process contains a large amount of unreacted calcium oxide or free lime.

  When recycling desulfurized slag, it is important to accurately determine the particle size distribution of these substances. Conventionally, various methods have been proposed as means for classifying fine powder with high efficiency. As one of the classification methods, there is known a vibration sieve classification method in which powder is classified by swinging and rotating the sieve layer. However, in the vibration sieve classification system, powder aggregates and segregates due to the influence of moisture acting between the powder particles, van der Waals force, electrostatic force, etc., and clogging of the sieve occurs. This causes a problem that the classification efficiency is lowered.

  Conventionally, various techniques for reducing or eliminating clogging of the sieve have been proposed for such problems.

  In Patent Document 1, a brush disk in which a brush is implanted is arranged on a mesh screen, and the brush disk is allowed to move by rotating the mesh screen in a horizontal swinging manner. A scraping technique is disclosed. Patent Document 1 discloses that an annular resonance ring is provided at the bottom of the sieve layer and ultrasonic vibration is applied to the resonance ring.

  Patent Document 2 discloses that mesh screens having different mesh sizes are arranged in multiple stages, and backwash air is blown onto the mesh screen to prevent the mesh screen from being clogged.

Japanese Patent No. 2882581 JP 2002-35698 A

  However, in the apparatus of Patent Document 1, when the apparatus is used for a long time, the brush may be damaged or worn and mixed into the separated particles as a foreign substance. In addition, since the brush must be replaced regularly, there is a problem that the running cost increases.

  Further, the apparatus of Patent Document 2 requires a large facility such as a blower for generating backwash air, and has a problem that initial cost and running cost increase. In addition, it is necessary to install a bug filter so that fine powder does not enter the blower, and it is necessary to periodically maintain the bag filter.

  Therefore, an object of the present invention is to reduce clogging of a sieve screen with a simple configuration and improve classification efficiency and throughput.

In order to achieve the above object, the present invention has the following features.
[1] A mesh sieve provided with at least one sieve for sieving powder;
An actuator for applying vibration to the mesh screen;
A control unit for generating a drive signal for driving the actuator;
The powder sieving apparatus, wherein the driving signal is a rectangular wave.
[2] The powder sieving device according to [1], wherein the frequency of the drive signal is 10 Hz to 20 kHz.
[3] The powder sieving device according to [1] or [2], wherein the frequency of the drive signal is set to an integer multiple of a frequency at which the classification efficiency of the sieve is maximized.
[4] The mesh screen includes a first screen and a second screen,
The actuator is provided in common for the first sieve and the second sieve,
The control unit is configured to output a drive signal of an integral multiple of a frequency at which the classification efficiency of the first sieve is maximized to an actuator, and an integral multiple of a frequency at which the classification efficiency of the second sieve is maximized. The powder sieving device according to any one of [1] to [3], wherein the second mode in which the drive signal is output to the actuator is switched at a predetermined time.
[5] A rectangular wave drive signal is input to an actuator that vibrates a mesh screen provided with at least one screen for screening powder.
A powder sieving method, wherein the actuator is vibrated to screen the powder.
[6] The powder sieving method according to [5], wherein the frequency of the drive signal is 10 Hz to 20 kHz.
[7] The powder sieving method according to [5] or [6], wherein the frequency of the drive signal is set to an integer multiple of a frequency at which the classification efficiency of the sieve is maximized.
[8] Using a powder sieving apparatus including a first sieve and a second sieve, and an actuator provided in common to the first sieve and the second sieve,
A first mode in which the drive signal having an integer multiple of the frequency at which the classification efficiency of the first sieve is maximized is output to the actuator; and the drive signal having an integer multiple of the frequency at which the classification efficiency of the second sieve is maximized. The powder sieving method according to any one of [5] to [7], wherein the second mode to be output to is switched at a predetermined time to perform powder sieving.

  According to the present invention, clogging of a sieve screen can be reduced with a simple configuration, and classification efficiency and throughput can be improved.

It is a figure which shows the structure of the powder sieving apparatus which concerns on embodiment of this invention. It is a figure which shows the drive signal input into the actuator of the powder sieving apparatus which concerns on embodiment of this invention. It is a figure which shows the drive signal produced | generated by the function generator.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  The powder sieving apparatus according to the present embodiment includes a mesh screen 1, an actuator 2, a coupling material 3, and a control unit 7. The powder sieved by the powder sieving device is, for example, a powder of 10 mm or less.

  The mesh screen 1 has three-stage screens 1a, 1b, 1c and a screen receiver 1d. The sieves 1a, 1b, and 1c are installed at a predetermined interval in the vertical direction. The sieves 1a, 1b, and 1c have a mesh for sieving the powder, and the meshes of the sieves 1a, 1b, and 1c are arranged so as to become finer as they go downward. The sieve receiver 1d is arranged under the lowermost sieve 1c and receives the powder that has passed through all the sieves 1a, 1b, and 1c and dropped downward.

  The actuator 2 is attached to the mesh screen 1 via a coupling material 3. The actuator 2 is controlled by the control unit 7 and controlled to vibrate at an arbitrary frequency and amplitude. The mesh screen 1 provided with the actuator 2 vibrates at an arbitrary frequency and amplitude. In the present embodiment, the actuator 2 is shared by the plurality of sieves 1a, 1b, and 1c, and all the sieves 1a, 1b, and 1c vibrate at the same frequency and amplitude due to the vibration of the actuator 2.

  The coupling material 3 is preferably made of grease or water.

  The control unit 7 includes an amplifier 4, a function generator 5, and a display unit 6. The amplifier 4 amplifies the drive signal generated by the function generator 5 to a predetermined amplitude, and outputs the amplified signal to the actuator 2 as a drive signal. The function generator 5 generates a drive signal for controlling the actuator 2 and outputs the generated drive signal to the actuator 2 via the amplifier 4.

  The display unit 6 displays control information of the powder sieving device such as a drive signal generated by the function generator 5.

  Next, the drive signal generated by the function generator 5 and amplified by the amplifier 4 will be described. The drive signal is set so that the classification efficiency of the respective sieves 1a, 1b, and 1c is maximized. Here, the classification efficiency is defined as the amount of powder below the sieve (sieving tray 1d) after sieving for a predetermined time / the amount of powder below the sieve in the sample (one sieve).

  Preliminary experiments are performed on the respective sieves 1a, 1b, and 1c, and the frequency of the drive signal that maximizes the classification efficiency is examined. Then, a drive signal is generated using the frequency of the drive signal at which the classification efficiency is maximized and a frequency that is an integral multiple of the frequency of the drive signal at which the classification efficiency is maximized, and the actuator 2 is driven.

  Moreover, since the frequency of the drive signal that maximizes the classification efficiency varies depending on the amount and weight of the powder placed on the sieves 1a, 1b, and 1c, the powder to be sieved or equivalent powder Most preferably, the body is placed on the sieves 1a, 1b, and 1c and the frequency of the drive signal at which the classification efficiency is maximized is examined.

  The drive signal input to the actuator 2 is preferably a rectangular wave as shown in FIG. Furthermore, the frequency of the drive signal is preferably 10 Hz to 20 kHz. When the sieve is vibrated at a frequency in the ultrasonic region as in the past, the amplitude cannot be increased due to the configuration of the machine, but in this embodiment, the frequency of the drive signal is set to 10 Hz to 20 kHz. The sieve can be vibrated with a certain level of amplitude and can be efficiently screened.

  FIG. 3 is a diagram illustrating a drive signal generated by the function generator 5. The function generator 5 changes the frequency and amplitude of the drive signal for each sieve, and generates the optimum frequency and amplitude of the drive signal for each sieve 1a, 1b, and 1c.

  Specifically, as shown in FIG. 3, in the first mode, a driving signal having a frequency that maximizes the classification efficiency of the sieve 1a is generated for a certain period of time and output to the actuator 2. In the second mode, the sieve 1b A drive signal having a frequency at which the classification efficiency is maximized is generated for a certain period of time and output to the actuator 2. To do. Thereby, the drive signal of the optimal frequency of the some sieves 1a, 1b, and 1c is generable with the one actuator 2. FIG. In this way, by switching from the first mode to the third mode, a single actuator 2 is used to generate an optimal drive signal for a plurality of sieves.

  In FIG. 3, the amplitudes of the first mode to the third mode are all the same. However, the amplitude may be changed from the first mode to the third mode. Further, the time lengths of the first mode to the third mode may be the same or different from each other. In the example of FIG. 3, the first mode to the third mode are shown once, but it may be configured to repeatedly switch from the first mode to the third mode. In this case, it is not necessary to repeat the first mode to the third mode the same number of times. For example, the first mode may be set only once, and the second mode and the third mode may be repeated twice.

  Next, the effect of this embodiment configured as described above will be described. In the powder sieving device according to the present embodiment, the waveform input to the actuator 2 is a rectangular wave. Here, since the direction of the vibration of the screen of the rectangular wave changes sharply at the edge portion of the signal, the screens 1a, 1b, and 1c are vibrated more vigorously than other waveforms such as a sine wave and a triangular wave. be able to. Thereby, clogging of the powder can be eliminated or reduced, and the powder classification efficiency and throughput can be improved.

  Further, in the powder sieving apparatus according to the present embodiment, the actuator 2 is vibrated with a drive signal having a frequency at which the classification efficiency of each of the sieves 1a, 1b, and 1c is maximized. Therefore, it is possible to efficiently vibrate the sieves 1a, 1b, and 1c, to eliminate or reduce clogging of the powder, and to improve the powder classification efficiency and throughput.

  Further, since it is not necessary to provide a brush for preventing clogging as in the prior art, there is no possibility of contamination due to such wear. Furthermore, a large-scale device like a conventional blower is not necessary.

  Further, in the powder sieving device according to the present embodiment, the drive signal of the actuator 2 is switched to a frequency at which the classification efficiency of each of the sieves 1a, 1b and 1c is maximized. Thereby, the drive signal of the optimal frequency can be supplied to the several sieves 1a, 1b, and 1c with the one actuator 2. FIG.

  The present invention is not limited to the above-described embodiment, and various design changes can be implemented. Specifically, in the above-described embodiment, one actuator 2 is shared by the plurality of sieves 1a, 1b, and 1c. However, the actuator 2 is provided for each sieve 1a, 1b, and 1c. May be. In this case, the function generator 5 does not need to switch the frequency of the drive signal as shown in FIG. 3, and a different optimum drive signal is supplied to the actuator 2 provided for each of the sieves 1a, 1b, and 1c. That's fine.

  In the above-described embodiment, the frequency of the drive signal of the actuator 2 is switched to a frequency at which the classification efficiency of each of the sieves 1a, 1b, and 1c is maximized every predetermined time. It is not necessary to switch to a frequency that maximizes the classification efficiency of all sieves. In the present invention, if the actuator 2 is driven at a predetermined time so that the frequency at which the classification efficiency of any one of the sieves is maximized, the clogging of the powder is eliminated or reduced, and the classification efficiency and processing of the powder are reduced. The effect of the present invention that the amount can be improved can be achieved.

  The classification efficiency may be the final amount of powder under the sieve (sieving tray 1d) / the amount of powder below the sieve in the sample (one sieve).

  The drive signal using the rectangular wave according to the present invention was compared with the drive signal using the sine wave and the triangular wave used as a comparative example. Using the same frequency and amplitude rectangular wave (invention example), sine wave (comparative example 1) and triangular wave (comparative example 2) drive signals, the same powder is screened by a sieve for a unit time, Each classification efficiency was examined. Here, the sieving time is 1 minute. As a result, the classification efficiency was 46% for the rectangular wave (example of the present invention), 30% for the sine wave (comparative example 1), and 10% for the triangular wave (comparative example 2). As a result, it was found that high sieving efficiency can be obtained when a rectangular wave is used as the drive signal.

DESCRIPTION OF SYMBOLS 1 Net sieve 1a, 1b, 1c Sieve 1d Sieve holder 2 Actuator 3 Coupling material 4 Amplifier 5 Function generator 6 Display part 7 Control part

Claims (4)

A net sieve having at least two sieves for sieving the powder;
An actuator for applying vibration to the mesh screen;
A control unit for generating a drive signal for driving the actuator;
The drive signal is a rectangular wave,
The mesh screen includes a first screen and a second screen,
The actuator is provided in common for the first sieve and the second sieve,
The control unit is configured to output a drive signal of an integral multiple of a frequency at which the classification efficiency of the first sieve is maximized to an actuator, and an integral multiple of a frequency at which the classification efficiency of the second sieve is maximized. A powder sieving apparatus, wherein the second mode of outputting the drive signal to the actuator is switched at a predetermined time .   The powder sieving apparatus according to claim 1, wherein the frequency of the driving signal is 10Hz to 20kHz. A rectangular wave drive signal is input to an actuator that vibrates a mesh screen provided with at least two sieves for sieving powder.
A powder sieving method in which the actuator is vibrated to screen the powder by applying vibration to the sieve,
Using a powder sieving device provided with an actuator provided in common to the first sieve and the second sieve, and the first sieve and the second sieve,
A first mode in which the drive signal having an integer multiple of the frequency at which the classification efficiency of the first sieve is maximized is output to the actuator; and the drive signal having an integer multiple of the frequency at which the classification efficiency of the second sieve is maximized. The powder sieving method is characterized in that the second mode to be output to is switched at a predetermined time to screen the powder. The powder sieving method according to claim 3 , wherein the frequency of the driving signal is 10Hz to 20kHz.

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