JP5838986B2 - Operation control method of vibration sieve device - Google Patents

Description

  The present invention relates to an operation control method for a vibration sieve device used for sizing and sorting of steel raw materials.

  In a steel mill, many vibrating screen devices are used for sizing and sorting steel materials such as coke and sintered ore. A vibration transmission member connected to a drive mechanism having a motor, a shaft, and the like is attached to the vibration sieve in order to give vibration. When the vibration sieve device is operated for a long time, the steel material adheres to the vibration sieve, and the weight fluctuates at the front, rear, left and right parts of the vibration sieve. At the beginning of vibration of the vibrating screen, when the weights at the front, rear, left and right parts are the same, the vibration acts on all parts in the same way. An amplitude difference and a phase difference occur between vibrations in the part. In that case, an abnormal load may be applied to the part of the vibration sieve, particularly the part to which the vibration transmitting member is connected, and the part may be damaged such as cracks. A great deal of damage occurs.

  In Patent Document 1, a vibration detector that detects vibration is arranged in each of a plurality of portions of a vibration sieve that is vibrated by a vibration exciter, and vibration outputs from the vibration detectors are compared, and vibration is detected. A method of monitoring a vibration sieve for determining the vibration state of the sieve has been proposed. In the monitoring method, the maximum amplitude and phase of the output vibration are compared to detect that an abnormality has occurred during operation of the vibration sieve. It is described that by comparing the maximum amplitude of vibration, it is possible to detect an imbalance in the vibration sieve with higher sensitivity than when comparing the phase of vibration.

JP 2008-161757 A

  According to the invention of Patent Document 1, the vibration sieve is stopped when vibration exceeding the allowable limit is applied to two parts of the vibration sieve. However, in such a case, if the operation of the vibrating sieve is stopped, operations such as sizing and sorting of the steel raw material are stopped. The invention of Patent Document 1 does not relate to an operation control method for a vibration sieve device that can prevent the vibration sieve from being damaged and can be operated for a long time and have a long service life. There is an actual situation that a technology for reliably preventing this and realizing both long-time operation and long life has not yet been established.

  The present invention has been made in view of this situation, and an object of the present invention is to provide a vibrating sieve device that reliably prevents damage to the vibrating sieve and that achieves both long-time operation and long life of the vibrating sieve. It is to provide an operation control method.

  The inventors of the present invention have inferred that the phase difference has a greater influence on the cracks generated in the vibrating screen than the difference in amplitude of vibration detected at two parts of the vibrating screen. This is because even if the amplitude difference between the vibrations at the two parts is large, if the two vibrations are in the same phase, it is difficult for the vibration sieve to be applied with a force enough to cause a crack. When the phases of vibration are different, it is considered that tensile vibration and compressive stress are generated in the vibrating screen due to the two vibrations, and there is a possibility that the vibrating screen may be strong enough to cause a crack. It is. Then, the inventors have clarified the allowable limit of the vibration sieve, and have completed the present invention to vibrate the vibration sieve so that the phase difference between the vibration waves generated in the two parts is less than the allowable limit. .

That is, the gist of the present invention for solving the above problems is as follows.
An operation control method of a vibration sieve device comprising a vibration sieve and a vibration detector for detecting vibration of a portion of the vibration sieve, the limit of the vibration sieve based on the shape and material of the vibration sieve in advance Obtaining the allowable stress, obtaining the relationship between the phase difference of the vibration wave of the two parts and the generated stress of the vibrating sieve, obtaining the limit phase difference corresponding to the limit allowable stress based on the relationship, An operation control method for a vibration sieve device, wherein the vibration sieve is vibrated so that a phase difference of vibration waves detected from vibration detectors arranged at two parts is equal to or less than the limit phase difference.

  According to the present invention, it is possible to reliably prevent the vibration sieve from being damaged, to achieve both long-time operation and long life of the vibration sieve device, and to maintain a high yield in the sizing and sorting of steel raw materials. Is done.

It is a top view of a vibration sieve apparatus. It is a side view of the vibration sieve apparatus shown in FIG. 5 is a graph showing the relationship between a direct stress range Δσ and a stress repetition number N. It is a graph which shows the relationship between stress and phase difference. It is a graph which shows the waveform of the vibration detected by two vibration detection parts. It is a graph which shows the waveform of the vibration detected by two vibration detection parts after correcting a phase difference.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a plan view of the vibrating sieve device, and FIG. 2 is a side view of the vibrating sieve device shown in FIG. The vibration sieve device 1 includes a vibration sieve 2, a drive mechanism 3, and a plurality of vibration detectors 5 a to 5 d that are arranged in a plurality of portions 4 a to 4 d of the vibration sieve 2 and detect vibrations. Hereinafter, the vibration detector is also simply referred to as “5”, and the vibration detection portion where the vibration detector is disposed is also simply referred to as “4”. For the description of the vibration sieve device 1, in FIG. 1, the upper side of the paper is the right side of the vibration sieve 2, the lower side of the paper is the left side of the vibration sieve 2, the left side of the paper is the front side of the vibration sieve 2, and the right side of the paper is the vibration sieve 2. In FIG. 2, the left side of the paper is the front side of the vibration sieve 2, the right side of the paper is the rear side of the vibration sieve 2, the back side of the paper is the right side of the vibration sieve 2, and the front side of the paper is the left side of the vibration sieve 2. .

  As shown in FIG. 2, the vibrating sieve 2 is inclined and vibrates at four locations, namely, [1] front right end, [2] rear right end, [3] front left end, and [4] rear left end. The sieve 2 is attached to a column 31 provided with an elastic member 31 a such as a spring by a bolt and supported by the column 31. A steel raw material 22 is supplied to the vibration sieve 2, and the steel raw material 22 is selected by the vibration sieve 2. Further, bearings 25 are provided at both ends of the center portion in the longitudinal direction of the vibration sieve 2, and vibrations from the drive mechanism 3 are transmitted through the bearings 25, and the steel raw material 22 is reliably selected by the vibrations.

  As shown in FIG. 1, a plurality of through holes 21 are formed in the vibration sieve 2, and the steel raw material 22 is supplied from the steel raw material supply port 23 to the rear portion of the vibration sieve 2 as shown in FIG. 2. . While the steel raw material 22 is rolling down on the surface inclined from the rear side to the front side of the vibration sieve 2, the steel raw material 22 a smaller than the through hole 21 falls from the vibration sieve 2 through the through hole 21, and the through hole 21. The larger steel material 22b falls on the vibrating sieve 2 and falls forward. Side walls 24 are provided at the left and right ends of the vibrating sieve 2 so that the steel raw material 22 does not fall from the left and right ends.

  As shown in FIG. 2, a conveying device 8 a is disposed below the vibrating screen 2, and the steel raw material 22 a falls on the conveying device 8 a below the vibrating screen 2 and at both front and rear ends thereof. In addition, a guide plate 9 is arranged. Further, a transport device 8b is disposed in front of the vibration sieve 2. The transport device 8a transports a relatively small steel material 22a to the next process facility, while the transport device 8b transports a relatively large steel material 22b to the next process facility.

  While the steel raw material 22 is rolling down on the vibrating screen 2, the vibrating screen 2 is vibrated. Next, the drive mechanism 3 that generates this vibration will be described. The drive mechanism 3 includes a motor 32, a gear box 33, and a shaft 34. As shown in FIG. 1, the shaft of the motor 32 supported by the support base 37 is connected to the shaft protruding from the gear box 33 via a belt 35. Through the belt 35, the rotational force of the motor 32 is transmitted to the shaft of the gear box 33 and transmitted to the shaft 34 protruding from the gear box 33 to the vibrating screen 2 side, and the shaft 34 rotates. The gear box 33 has a known structure, and can appropriately change the rotational speed of the motor 32 and transmit the rotational force whose speed has been changed from the motor 32 to the shaft 34.

  A bearing 25 is attached to the side wall 24 in the center portion in the longitudinal direction of the vibration sieve 2, and a shaft 34 is fitted to the bearing 25. The shaft 34 between the bearing 25 and the gear box 33 is attached with an eccentric weight 36 having a biased center of gravity, such as a sector. When the shaft 34 rotates, a whirling load is generated by the eccentric weight 36, and circular vibration is generated in the shaft 34. The vibration generated in the shaft 34 is transmitted to the bearing 25, and the vibration sieve 2 vibrates. Since this elastic member 31a is provided in the middle of the column 31, the vibration sieve 2 vibrates in the front-rear and up-down directions using the bearing 25 (shaft 34) as a vibration source, as shown in FIG.

  As the vibration sieve 2 continues to operate for a long time, the steel raw material 22 adheres to various parts of the vibration sieve 2, and the weight changes at the front, rear, left and right parts of the vibration sieve 2. At the beginning of the operation of the vibration sieve 2, when the weights at the front, rear, left and right parts are the same, the vibration acts similarly at any part of the vibration sieve, but the weights at the front, rear, left and right parts of the vibration sieve 2 are the same. If they are different, an amplitude difference or a phase difference is generated between the vibrations in these parts. Then, an abnormal load is applied to the part of the vibration sieve connected to the device other than the vibration sieve, for example, the part of the vibration sieve 2 to which the bearing 25 is attached, the part to which the support 31 is attached, and the like. Damages such as cracks may occur in those parts.

  Therefore, in the present invention, in order to prevent the occurrence of such damage, the above vibration is managed in the following steps (1) to (3).

Process (1)
Based on the shape and material of the vibrating sieve 2, the limit allowable stress of the vibrating sieve 2 is obtained. The shape and material of the vibration sieve 2 are the shape and material of a part where an abnormal load is particularly likely to be applied due to vibration.

Step (2)
Two vibration detectors 5 are selected from a plurality of vibration detectors 5 attached to a plurality of parts of the vibration sieve 2, and vibrations are generated at the two vibration detection parts 4 where the vibration detectors 5 are arranged. The relationship between the wave phase difference and the stress generated at the site described in step (1) is obtained in advance by simulation such as FEM analysis or actual measurement such as a strain gauge. Based on this relationship, a critical phase difference corresponding to the critical allowable stress obtained in step (1) is obtained. The vibration detection part 4 refers to a part that can detect the vibration of the vibration sieve 2 or a part that vibrates together with the vibration sieve 2. The vibration detection part 4 of the vibration sieve 2 is not part of the vibration sieve 2 such as the surface of the side wall 24 of the vibration sieve 2 or the back surface of the vibration sieve 2 or part of the vibration sieve 2, but vibrates together with the vibration sieve 2. A portion of the support column 31 is included.

  In the present embodiment, as shown in FIG. 1, the upper surface of the support 31, the vibration sieve 2, [1] front right end, [2] rear right end, [3] front left end, [4] rear left end, Four representative parts are adopted as the vibration detection parts 4, and the vibration detector 5 is arranged in these vibration detection parts 4. Hereinafter, among the four vibration detectors 4, the front right end is 4a, the rear right end is 4b, the front left end is 4c, and the rear left end is 4d. The right end is 5a, the rear right end is 5b, the front left end is 5c, and the rear left end is 5d.

Process (3)
A first vibration wave detected by the first vibration detector 5 and a second vibration wave detected by the second vibration detector 5 are arranged at the two vibration detection sites 4 selected in the step (2). The vibrating sieve is vibrated so that the phase difference between and becomes equal to or less than the limit phase difference obtained in the step (2).

  The steps (1) to (3) will be described in detail below.

<Step (1)>
FIG. 3 is an example of a fatigue design curve of a metal material, and is an example of a graph showing the direct stress range Δσ on the vertical axis and the stress repetition number N on the horizontal axis. The direct stress range Δσ indicates the stress amplitude generated at the measurement site, and the stress repetition number N is the stress caused by fatigue when the stress in the corresponding direct stress range Δσ is repeatedly applied to the target metal material. The number of repetitions leading to the fracture is shown. The fatigue design curve can be obtained from known literature, for example, “Fatigue Design Guidelines for Steel Structures” of the Japan Steel Structure Association (JSSC).

  This fatigue design curve is selected (determined) based on the shape and material of the portion of the vibration sieve 2 that is likely to be subjected to an abnormal load due to vibration. As this portion, for example, attention is paid to the portion of the vibrating sieve 2 to which the bearing 25 is attached. The shape of the part includes not only the shape of the side wall 24 but also the dimensions of the part such as the thickness of the side wall 24 and a mode in which a bearing 25 is attached to the side wall 24. As shown in FIG. 2, the part attached to the side wall 24 with the bolts penetrating the bearing 25 can be said to be a joint part where the case of the bearing 25 and the plate member of the side wall 24 are joined by a plurality of bolts. The material of the part includes the material of the vibration sieve 2, the side wall 24 and the bearing 25. Since durability is required, the entire vibrating screen 2 is made of metal, but the material includes the type of metal and the state in which welding repair has been performed in the past.

The so-called metal material strength class Δσf is determined by the shape and material as described above, and a fatigue design curve corresponding to the strength class Δσf is selected (determined). In the fatigue design curve, a sufficiently large stress repetition number N is obtained so that the direct stress range Δσ gradually approaches a certain value. When the stress repetition number N on the horizontal axis exceeds 10 ⁷ and becomes approximately 10 ⁸ to 10 ⁹ , the corresponding direct stress range Δσ gradually approaches a constant value. This graph shows that even when the stress in the direct stress range Δσ below this certain value is applied to the metal material, the metal material is unlikely to break, and the vibration sieve 2 is subject to an abnormal load. Is assumed to be the metal material of the graph, and the stress in the direct stress range Δσ is defined as the limit allowable stress that is a constant value that is difficult to break. In the example of FIG. 3, the limit allowable stress is 50 MPa.

<Step (2)>
In the present invention, in the step (3), vibration waves at a plurality of parts of the vibration sieve 2 are observed, and the vibration sieve 2 is vibrated so as to adjust the shape of the vibration waves.

  Attention is paid to the phase difference between two vibration waves at two vibration detection parts 4 among the plurality of vibration detection parts 4. As the two vibration detection parts 4 to be focused on, a combination of the vibration detection part 4b at the rear right end and the vibration detection part 4c at the front left end, or a combination of the vibration detection part 4d at the rear left end and the vibration detection part 4a at the front right end. Are preferred. This is because the vibration detection parts 4b, 4c or the vibration detection parts 4a, 4d, which are positioned diagonally across the shaft 34 and the main body of the vibration sieve 2, are the two parts farthest from the vibration source shaft 34. This is because a difference is likely to occur in the vibrations at the two parts, and the difference becomes large. By adjusting the shape (phase difference) of the vibration wave in these parts, it is easy to suppress the stress generated in the part of the vibration sieve 2 where an abnormal load is easily applied.

  In the present embodiment, since the motor 32 serving as a vibration power source is present on the left side of the vibration sieve 2, the left side of the vibration sieve 2 is more likely to vibrate than the right side. Differences in vibration are likely to occur. Furthermore, the further away from the shaft 34, the more the vibration at that portion tends to be larger than the vibration generated at the shaft 34. For this reason, a difference in vibration tends to occur between the front end and the rear end of the vibrating sieve 2. If the phases of the two vibration waves are different, the force generated by the two vibrations becomes tensile and compressive stresses on the vibrating screen, which is strong enough to cause a crack in the vibrating screen. Because.

  In the present embodiment, the parts of the vibration sieve 2 for observing the vibration wave are the vibration detection parts 4b and 4c, and the shaft of the parts of the vibration sieve 2 to which the bearing 25 is attached as the parts that are likely to be subjected to abnormal loads. It is assumed that the portion is closer to 34. When two vibrations having different phase differences are generated in the vibration detection portions 4b and 4c, stress generated in a portion where an abnormal load is easily applied is obtained in advance. FIG. 4 is an example of a graph showing the relationship between the stress generated at the part and the phase difference of vibration at the vibration detection parts 4b and 4c. A phase difference corresponding to a stress equal to the limit allowable stress is obtained from FIG. 4, and this phase difference is defined as a limit phase difference.

  The relationship between the stress and the phase difference shown in FIG. 4 can be obtained, for example, by simulation by numerical calculation such as FEM analysis. Based on the specifications of the vibration sieve 2, the amplitude and frequency of vibration applied to the vibration sieve 2 are determined. Other settings required for simulation are also determined by the specifications. Note that the directions of the two vibration waves obtained at the two vibration detection sites in step (2) may be either the front-rear or vertical direction, but are the same as the directions of the vibration waves observed in the next step (3). Is preferred. In the next step (3), when the vibration sieve 2 is actually operated, a simulation can be performed with the amplitude and frequency of the vibration wave to be set.

  When the amplitude of vibration in the two parts is the same, the frequency of one vibration wave is fixed, and the other frequency is changed, the phase difference increases. As can be seen from the graph of FIG. 4, when the frequencies of the two vibration waves are the same (phase difference 0 °), the generated stress is the minimum value, and the phase difference increases in the simulation. It can be seen that the generated stress increases from the minimum stress value. In the example of FIG. 3 in step (1), 50 MPa is obtained as the limit allowable stress, and in the graph of FIG. 4, a phase difference of 35 ° corresponding to the limit allowable stress of 50 MPa is determined as the limit phase difference.

<Step (3)>
FIG. 5 is an example of a graph showing waveforms of vibrations detected at the vibration detection portions 4b and 4c. FIG. 6 is an example of a graph showing the waveforms of vibrations detected at the vibration detection portions 4b and 4c after the phase difference is corrected. The first vibration wave detected from the vibration detector (first vibration detector) 5b at the rear right end arranged at the vibration detection part 4b is obtained, and similarly the vibration at the front left end arranged at the vibration detection part 4c. A second vibration wave detected by the detector (second vibration detector) 5c is obtained.

  As shown in FIG. 5, when the phase difference between the first vibration wave and the second vibration wave is 90 °, the eccentric weight 36 already attached to the shaft 34 is changed to a different shape, The number of rotations of the shaft 34 is changed by changing the gear in the gear box 33 and the like, as shown in FIG. 6, detected from the vibration detectors 5b and 5c arranged in the two vibration detection parts 4b and 4c. The vibration sieve 2 is vibrated so that the phase difference of the vibration wave to be generated is equal to or less than the limit phase difference obtained in the step (2) (for example, a phase difference of 4 °). Thereby, it is possible to reliably prevent damage to a portion connected to a device other than the vibration sieve 2 among the portions of the vibration sieve 2, and to make the vibration sieve device 1 operate for a long time and prolong its life. An industrially beneficial effect is brought about.

  As the vibration detector 5, a piezoelectric vibration detector or the like may be used, and the vibration detector 2 is a vibration detector capable of measuring vibrations in the front-rear and left-right directions and the up-down direction. A signal line to a display mechanism (not shown) is connected to the vibration detector 5, and waveform signals in the front-rear direction and the up-down direction are detected from the signal line, and the display mechanism is shown in FIGS. Display the vibration waveform.

  In the above embodiment, the fatigue design curve is selected as the shape of the vibration sieve based on the aspect of attaching to the side wall 24 with the bolts penetrating the bearing 25, but the present invention is not limited to this form, and the bearing 25 is connected to the side wall 24. The graph (fatigue design curve) shown in FIG. 3 may be determined based on the shape of being attached by welding.

  Moreover, in the said embodiment, although paying attention to the site | part to which the bearing 25 is attached as a site | part of the vibration sieve 2 which calculates | requires a limit allowable stress, this invention is not restricted to this form, The support | pillar 31 is attached. It is also possible to obtain the limit allowable stress at a part where a large load is applied due to vibration, such as a part that is present.

  Furthermore, in the above-described embodiment, the vibration detection part where two vibration waves are required is the right rear part and the left front part across the vibration sieve 2 body, and the upper part of the column 31. This is not limited to this part, and any two parts that generate vibration may be used. In addition, when an arbitrary number of parts are selected from a plurality of parts, the vibration sieve 2 is obtained in the steps (1) to (3) in any combination of two parts that are combined from the selected parts. It is preferable to manage the vibration. This is because the vibration sieve 2 may be broken if vibration exceeding the limit allowable stress occurs even in any one combination of the two parts. For example, when three sites are selected, the number of combinations of two sites combined from the three sites is three. It is preferable not to generate vibration exceeding the limit allowable stress even in the two parts of any of these three combinations.

  In the conventional method for detecting an abnormality of a vibration sieve, there is a possibility that the vibration sieve device may be made abnormal without taking into consideration the stress generated in a portion where an abnormal load is applied. For this reason, even though it is possible to prevent the vibration sieve from being damaged, it is not possible to specify the maximum allowable stress within a range where the vibration sieve is not damaged, and the vibration sieve is limited to the limit where the damage does not occur. It is impossible to achieve both long operation and long life using On the other hand, by specifying the maximum allowable stress within a range that does not cause damage to the vibrating screen according to the present invention, the vibrating screen is vibrated so as not to exceed the allowable stress, so that the vibrating screen is damaged. It is possible to make maximum use of the vibration sieving apparatus and to operate for a long time and to prolong the service life.

DESCRIPTION OF SYMBOLS 1 Vibration sieve apparatus 2 Vibration sieve 3 Drive mechanism 4 Vibration detection part 4a Vibration detection part 4b (Rear right end) Vibration detection part 4c (Front left end) Vibration detection part 4d (Rear left end) Vibration detection part 5 Vibration detector 5a Vibration detector 5b (front right end) Vibration detector 5c (rear right end) vibration detector 5d (front left end) vibration detector 5d (rear left end) vibration detectors 8a and 8b Transport device 9 Guide plate 21 Through Hole 22 Steel raw material 22a (relatively small) Steel raw material 22b (relatively large) steel raw material 23 Steel raw material supply port 24 Side wall 25 Bearing 31 Post 31a Elastic member 32 Motor 33 Gear box 34 Shaft 35 Belt 36 Eccentric weight 37 Support base

Claims (1)

An operation control method of a vibration sieve device comprising: a vibration sieve; and a vibration detector that detects vibration of a portion of the vibration sieve,
Based on the shape and material of the vibrating sieve in advance, obtain the limit allowable stress of the vibrating sieve,
Obtain the relationship between the phase difference between the vibration waves of the two parts and the generated stress of the vibrating sieve, and obtain a limit phase difference corresponding to the limit allowable stress based on the relationship,
An operation control method for a vibration sieve device, wherein the vibration sieve is vibrated so that a phase difference of vibration waves detected from vibration detectors arranged at the two parts is equal to or less than the limit phase difference.

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