Method for acoustically monitoring a crusher

Abstract

The invention relates to a passive acoustic monitoring method for continuous assessment of the state of a crusher. The method envisages placing a microphone on the housing of a crusher. Sound picked up by the microphone is amplified and passed through an analog-to-digital converter, after which it is analyzed by a control computer. A software algorithm of the computer categorizes the received sound into different types. The method is based on the structural characteristics of a crusher, where metal parts only come into contact with one another via an oil lubricant or sealing elements. The type of sound signal produced by the direct impact of metal on metal, which is distinguished by a high amplitude, is not characteristic of normal operation and is accurately registered by the control computer. Such a sound may indicate the presence of uncrushed material in the discharge gap, an imbalance among fastening elements, damage to the integrity of structural elements, and other such irregularities. On the basis of a sound image obtained, the operator of the crusher can decide upon the course of action to be taken. The technical result is the remote, continuous and easily implemented acoustic monitoring of the state of a crusher, and an increase in the scope of application.

Description

[0001] Method of acoustic control of crusher

[0002] The invention relates to the field of heavy engineering, to crushing and grinding equipment, in particular to methods for monitoring cone crushers, and can be used in technological processes in the construction and mining and processing industries.

[0003] It is known from the prior art that any cone crusher contains a housing with an outer cone and an inner crushing cone located inside it, the surfaces of which facing each other form a crushing chamber.

[0004] The internal crushing cone is mounted on a cone support, for example, a spherical one, and has a drive shaft connected to a drive transmission. The drive transmission sets the internal crushing cone in motion. From the feeder located above, the crushed material, under the action of its own weight, enters the crushing chamber, then into the finished product unloading zone located inside the housing.

[0005] The crusher body is the main supporting structure, all parts of which are connected to it: they are either fixed to the body directly, or are in contact with the body through other connected elements. The body is made of metal, in particular, of high-strength alloy cast steel. The structural elements and working parts of the crusher are also made of various types of metal, depending on their purpose, including various connecting elements, such as fasteners, bolts, pins.

[0006] All moving metal elements of the crusher operate using special sealing gaskets and oil lubricants, so they come into contact with each other only through a layer of lubricant.

[0007] An important task is to monitor the condition of the crusher and individual elements, as well as to monitor and adjust its operating parameters. As a rule, each crusher is controlled by a control computer and an operator.

[0008] During the operation of the crushing unit, the crushing surfaces wear out, and the fastening elements may also become loose, an uncrushable body may get into the crushing chamber, or the integrity of any structural element may be compromised. These and other reasons lead to the risk of an abnormal or emergency situation. In the event of an emergency, the crusher is forced to stop, the emergency element is searched for, after which dismantling, repair, and replacement of parts are carried out.

[0009] At present, in the event of an abnormal situation, the operator stops the unit and inspects the body and design parts. Such visual inspection has significant drawbacks and limitations, including those related to the influence of the human factor, as well as to the design features of the unit.

[0010] It is obvious that the possibility of constant remote monitoring, which would allow us to accurately determine the occurrence of an emergency situation, would significantly reduce the number of emergency situations and their consequences.

[0011] For such remote control, the present invention proposes to use a microphone and the features of the propagation of sound vibrations in various environments.

[0012] The prior art discloses the use of a microphone to adjust the parameters of a crushing unit.

[0013] For example, a patent for invention EP0391096 is known, priority date 1989-04-07 “METHOD FOR AUTOMATICALLY CONTROLLING THE CRUSHER CLEARANCE, DETERMINING THE GRANULAR SIZE, OF A CRUSHING MACHINE AND APPARATUS FOR CARRYING OUT THE METHOD”, which is taken as a prototype.

[0014] The prototype belongs to rotary, otherwise known as roller, crushers.

[0015] The roller crusher shown in Figure 1 included in the description of the prototype comprises a housing 1 in which a rotor 2 is arranged so as to be able to rotate around a horizontal axis 3. The rotor 2 is provided with four impeller rods, 4. otherwise called a beater. The striker 5, also called a crushing plate in professional information sources, is mounted so as to be able to rotate around an axis 6 above the rotor 2. The striker 5 is provided with wear plates 7 arranged on the side facing the rotor 2. The lowest of the wear plates 7a in combination with an imaginary cylindrical surface 8 described by the outer edges of the impeller rods 4 during rotation form a discharge gap 9. The width of the discharge gap 9 changes depending on the rotational position of the striker 5. The striker 5 moves as shown in the figure.3, with the help of an electric motor 10, a worm gear 11, a spindle 12, an elastic intermediate element 13 and an additional connecting link 14, pivotally attached to the striker 5. The control element 15 is located on the spindle 12, and the switching protrusion I6 is provided on the intermediate element 13.

[0016] In the drive mechanism 10, 11, 12 of the striker 5, a pulse counter is provided, consisting of a toothed disk 17 and an induction sensor 28. The induction sensor 28 tracks the movement of the striker 5 and evaluates its movement for the purposes of the adjustment process.

[0017] A microphone 18 is mounted on the body 1 of the crusher, which picks up sound from the body and converts this sound into electrical signals. As shown in the block diagram, figure 2, the sound signals from the microphone 18 pass through amplifiers 19 and 20, and then along two channels 21, 22, which lead to two signal separator devices 23, 24, which have different response thresholds.

[0018] The signal separator 23 has a relatively low response threshold, and passes weak sound signals that occur when there is no material in the crusher and when the crusher is idling. The corresponding signal is processed by the time switch 25 and sent to the control computer 27.

[0019] The signal separator 24 has a relatively high response threshold and therefore passes strong sound signals, for example, those arising as a result of the impact of the impeller rods 4 on the striker 5. Such strong signals are processed by the time switch 26 and are also sent to the control computer 27.

[0020] It is known from the prior art that during the process of crushing material in a roller crusher, wear of its working surfaces occurs, in particular the impeller rods 4 and wear plates 7. As a result, the distance between the said working surfaces, called the unloading gap 9, gradually increases and is therefore subject to adjustment.

[0021] For the purpose of adjustment, it is possible to move the striker 5 closer or further from the rotor 2. Before starting the process of adjusting the unloading gap 9, the crusher is freed from the crushed material.

[0022] The idle operation of the crusher without material is confirmed by a sound signal from the microphone 18 with a low noise level. The signal is processed by channel 21 and transmitted to the control computer 27. The computer 27 processes the received signal and gives an indication to move the striker 5 toward the rotor 2. The drive mechanism 10,11,12 moves the striker 5 toward the rotor 2 until the lowest of the wear plates 7a contacts the rotating rods of the impeller 4, and a striking sound is produced.

[0023] The characteristic strong sound of metal striking metal is recorded by microphone 18, passes through channel 22 and is sent to control computer 27. Computer 27 records this position of striker 5 and defines it as the fact of zero unloading gap. After which computer 27 gives a command to move striker 5 in the direction from rotor 2 to a distance corresponding to the required size of unloading gap 9.

[0024] The pulse counter 17, 28 participates in determining the current position of the striker 5 and setting the required size of the gap 9, the signals from which are also sent to the computer 27. Upon reaching the required position of the striker 5, the pulse counter 17, 28 sends a corresponding signal to the computer 27, which immediately gives an indication to stop the movement of the striker 5.

[0025] Thus, the adjustment of the size of the unloading gap 9 is carried out automatically based on sound signals initially received from the microphone 18 and processed by the control computer 27.

[0026] In the described prototype, signals received from a microphone mounted on the body help to diagnose the location of the working elements of the crushing unit in relation to each other, and to adjust the discharge gap.

[0027] The limitations of the prototype include a narrow range of acoustic applications, which help regulate only one of the crushing unit parameters.

[0028] The aim of the present invention is to create an effective passive acoustic method for continuous diagnostics of the condition of a crusher.

[0029] To achieve this goal, it is proposed to use the features of the propagation of sound vibrations in various environments, in particular the good ability of metals to conduct sound.

[0030] The prior art includes methods of passive acoustic monitoring based on the analysis of processes in the controlled object, for example vibrations or noises arising during operation, the so-called noise diagnostic method.

[0031] It is also known from the level of technology that any metals are capable of conducting a sound wave much faster than, for example, the air environment. This phenomenon can be used to diagnose processes occurring in the body of the crushing unit.

[0032] The body of the crusher is made of metal, in particular, high-strength alloy cast steel. The structural elements and working parts of the crusher are also made of different types of metal, depending on their purpose.

[0033] At the same time, all the parts of the crusher are connected to its body in one way or another: they are either installed in it directly or are in contact with the body through other connected elements. Various connecting elements, such as fasteners, bolts, pins, are also metal.

[0034] Therefore, the crushing unit can be considered on the one hand as a complex composite, but on the other hand as a conditionally single metal structure. During normal operation of the crusher, the metal parts of the machine never come into direct contact with each other, but only through the crushed material, through oil lubrication, or through non-metallic sealing elements.

[0035] Therefore, any abnormal situation in the crusher should be characterized by the fact that the metal elements of the machine structure come into contact with each other with the characteristic sound of metal hitting metal.

[0036] Therefore, if you place a microphone on the body of the crusher, you will be able to record any sound signals of various amplitudes with virtually no time delay: not only the standard noise generated during the crushing process, but also the sounds of metal machine parts hitting each other, the sounds of loose fasteners; and similar abnormal sounds.

[0037] In this case, it is advisable to equip the crusher's control computer with a special software algorithm that could interact with the sound signals received from the microphone, receive, analyze, and form diagrams. To do this, the sound signal received from the microphone must be amplified to a certain level and digitized.

[0038] Thus, with the help of a microphone, constant remote diagnostics of the crushing unit condition can be implemented, allowing to register abnormal situations at the earliest stages of the problem occurrence, in real time. As a result, the crusher operator will be able to monitor the occurrence and development of an abnormal situation and make a decision on the necessary actions. The set goal is solved by the Method of acoustic control of the crusher, including the installation of at least one microphone on the crusher body, passing the sound signal received from the microphone through a normalizer, made with the possibility of amplifying the sound level, then passing the said sound signal through an analog-to-digital converter, then feeding the said sound signal to the crusher control computer, equipped with a software algorithm made with the possibility of receiving, processing and analyzing sound signals,classification by the said software algorithm of the microphone sound signal into three sound categories, wherein the first sound category includes signals taken from a non-working crusher and characterizing the background noise level, the second sound category includes signals taken from a working crusher and characterizing the noise level of a crusher operating normally under load, the third sound category includes high-amplitude signals taken from a working crusher characterizing the occurrence of an abnormal situation; the formation by the crusher control computer, based on the results of the analysis of the sound signal, of a conclusion on the state of the crusher and its transmission to the operator, the operator making a decision on the necessary actions.

[0039] The acoustic monitoring method may include an additional difference consisting of installing a microphone on the crusher body in such a way that the sound-sensitive membrane of the microphone is directly adjacent to the crusher body.

[0040] The invention is illustrated by the following figures.

[0041] Fig. 1 is a sequential block diagram of the implementation of the method for acoustic diagnostics of a crusher.

[0042] Fig. 2 shows an example of a sound diagram of a real signal obtained during the acoustic diagnostics of a crusher.

[0043] The method of acoustic control of the crusher is implemented as follows.

[0044] Microphone 2 is mounted on body 1 of the crusher. It is advisable that the sound-sensitive membrane of microphone 2 be maximally isolated from environmental sounds. For this purpose, microphone 2 can be placed in a special casing that has sound-insulating properties on all sides, except for the side of the microphone with the sound-sensitive membrane facing directly to the surface of body 1 of the crusher.

[0045] Microphone 2 is connected to normalizer 3. Sound signals from microphone 2 are fed to normalizer 3. A sound normalizer in the context of the present invention is a tool that is intended to increase the volume of sound by a given number of times. Normalizer 3 amplifies the level of sound received from microphone 2 to values ​​required for its further processing.

[0046] From the normalizer 3, the sound signal is sent to the analog-to-digital converter 4. The analog-to-digital converter 4 converts the analog format of the sound wave into a digital signal. The analog-to-digital converter is connected to the control computer by any means, wired or wireless.

[0047] The audio signal is sent to the control computer 8 in digital format. The control computer 8 analyzes the received signal using the software algorithm installed on it, forms a conclusion about the crusher condition and transmits it to the operator. After that, the operator gives the control command for further actions.

[0048] During the analysis process, the software algorithm identifies three fundamentally different categories of sound signals coming into the computer 8 from the microphone 2, as shown in Fig. 1.

[0049] The first category of sound signals is schematically presented in block 5. This type includes signals taken from a non-working crusher, which reflect the background noise level around the unit. The crusher itself does not produce any sound signals when idle, but there is always a background sound from the environment, which is recorded by the sensitive sound-receiving membrane of microphone 2.

[0050] The second category of sound signals is schematically presented in block 6. This type includes the noise level picked up by microphone 2 from a normally operating crusher. A crusher operating under load creates a certain noise level, which in the normal mode of uninterrupted and trouble-free operation is a fairly strong, but relatively smooth sound signal. As was said above, during normal operation of the crusher, the metal parts of the machine never come into direct contact with each other, but only through the crushed material, through oil lubrication, or through sealing elements. Therefore, the sound is mainly generated when the crushed material comes into contact with the crushing surfaces.

[0051] The third category of sound signals is schematically presented in block 7. This type includes sound signals that reflect the occurrence of an abnormal situation in a working crusher. Almost any abnormal situation, including an emergency, in a crusher is characterized by the fact that the metal elements of the machine structure come into contact with each other with the characteristic sound of metal hitting metal.

[0052] As shown above, all elements of the crusher design are connected to its body in one way or another, and the process of crushing materials occurs at high drive speeds. Therefore, the impact sound from any metal elements and / or parts of the crusher that contact each other will be transmitted to the body. Various metal fasteners, bolts, pins that have lost their rigidity, have become loose or broken will also produce a characteristic sound of metal hitting metal, the sound of metal rattling and similar sounds, as well as an uncrushable metal body that has fallen into the discharge gap. Any such impacts of metal on metal inside the crusher cause sharp and strong amplitude surges in certain ranges of the sound spectrum, which are transmitted to the body and recorded by microphone 2.

[0053] Sound bursts of the third category can be single or multiple in time, it is important that the level of their amplitudes in this case significantly exceeds the level of normal noise of the crusher, in other words, the level of the amplitudes of the sound of the second category, block 6.

[0054] Fig. 2 is a graph of the combined sound wave of the second type, block 6, and the third type, block 7, received and processed by the software algorithm of the control computer. At the level of the background noise of the operating crusher, pronounced sound bursts are traced, caused by an emergency contact of two metal parts inside the unit.

[0055] From left to right in the sound diagram - normal operation, then a single blow A; then normal operation and two blows in a row B and C; then normal operation and a single blow D; and again normal operation of the crusher. The software algorithm of the control computer 8 is configured so that it can clearly distinguish between the different types of sound signals. In this case, the software algorithm can clearly distinguish the alarm signal of the third type, block 7, from any other sound signals emitted by the crusher during operation under any load or at idle, when starting and when stopping the crusher; and also distinguish the sound background around the idle crusher.

[0056] The logic of processing and analyzing information by the software algorithm is the standard logic of the “software comparator”, known from the prior art.

[0057] The software algorithm interacts with a pre-installed database containing libraries of digitized sounds, divided into permitted and prohibited sounds.

[0058] The software algorithm compares the incoming digitized audio signal with the samples available in the sound library and, based on the results of this comparison, divides the received sounds into categories.

[0059] Sounds classified by the algorithm as the first and second categories based on the comparison results are allowed and do not generate any reaction from the algorithm.

[0060] Sounds classified into the third category are not allowed, and if such a sound is detected, the algorithm generates a corresponding signal and transmits it to the crusher operator.

[0061] Information about the presence of category 3 sound is received by the operator, and then he makes a decision on the necessary actions.

[0062] The software algorithm records and saves the resulting audio track in a separate database, thus creating a specific library of sounds characteristic of a given unit.

[0063] Preferably, the software algorithm could broadcast the sound through external speakers and display a real-time sound diagram on the computer screen for additional visual monitoring.

[0064] The unit can be stopped to eliminate the malfunction or to release the non-crushable body.

[0065] Example of implementation of the invention.

[0066] An experiment on the practical implementation of the proposed solution was conducted on a cone crusher of the KMD 3000 type weighing 230 tons, installed in a closed room of the factory workshop. To implement the acoustic control method, a device was assembled in the form of a single one-volume plastic case.

[0067] The device housing contained a three-wire condenser electret microphone of the MKE-3 type with a built-in amplifier in the form of a field-effect transistor, which was connected to a normalizer implemented on the MAX9812L microcircuit; connected to an analog-to-digital converter. In this case, the MKE-3 microphone was structurally installed in such a way that it was located outside the device housing. For this purpose, a hole was made in the wall of the housing exactly to the size of the microphone, so that its sound-sensitive membrane was on the outside and tightly adjoined the crusher housing. Additionally, the device housing was equipped with four external mounting magnets, which securely held the device in place.

[0068] The device assembled in this way was connected to the power supply and to the control computer located in the operator's room of the workshop by wire. The control computer was equipped with a special software algorithm designed to process the received sound signals, record the sound track and output the sound diagram to the screen.

[0069] The crusher was put into operation under load. On the opposite side from the installed device, blows were applied to the body of the crusher operating under load using a metal hammer weighing 300 grams. The blows were applied in series of 10 blows at equal intervals. When listening to and analyzing the sound recording, all hammer blows were clearly audible; they stood out significantly as sharp splashes against the general background of sounds of the operating crusher. When viewing the sound diagram on the computer screen, strong splashes of the amplitudes of the sound signal at the moment of blows were clearly visible.

[0070] If necessary, to obtain a sound diagram of particularly high accuracy, or to work with large-sized machines, the device can be equipped with two or more microphones.

[0071] The main advantage of the proposed method and device is the ability to obtain information about the occurrence and development of an abnormal situation in the crusher at the earliest stage. This will allow the operator to make a decision to stop the unit and eliminate the malfunction when the problem has not yet developed and has not reached a critical scale, which makes it possible to significantly reduce the damage from an accident or avoid it altogether.

[0072] Also significant advantages are the ease of implementation and wide versatility of the method, allowing it to be used on various crushers.

Claims

Invention formula 1. A method for acoustic monitoring of a crusher, comprising installing at least one microphone on the body of the crusher, passing an audio signal received from the microphone through a normalizer configured to amplify the sound level, then passing said audio signal through an analog-to-digital converter, then feeding said audio signal to a control computer of the crusher equipped with a software algorithm configured to receive, process and analyze audio signals, classifying the microphone audio signal into three sound categories by said software algorithm, wherein the first sound category includes signals taken from an idle crusher and characterizing the background noise level, the second sound category includes signals taken from an operating crusher and characterizing the noise level of a crusher operating normally under load, and the third sound category includes high-amplitude signals taken from an operating crusher,characterizing the occurrence of an abnormal situation; the formation by the crusher control computer of a conclusion on the state of the crusher based on the results of the analysis of the sound signal and its transmission to the operator, the operator making a decision on the necessary actions, 2. A method for acoustic monitoring of a crusher according to claim 1, comprising installing at least one microphone on the crusher body in such a way that the sound-sensitive membrane of the microphone is directly adjacent to the crusher body.

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