Vibration is a complex oscillatory process that occurs when the center of gravity of a body or a system of bodies is periodically displaced from the equilibrium position, as well as when the shape of the body is periodically changed, which it had in a static position.

The reason for the excitation of vibrations is the unbalanced force effects arising from the operation of machines and units. Sources of vibration are reciprocating moving systems (crank mechanisms, hand drills, sealers, vibratory rammers, devices for packaging goods, etc.), as well as unbalanced rotating masses (electric and pneumatic grinding and cutting machines, cutting tools).

The main parameters of vibration, occurring according to a sinusoidal law, are: frequency, amplitude of displacement, speed, acceleration, oscillation period (time during which one complete oscillation occurs).

Depending on the contact of the worker with vibrating equipment, a distinction is made between local(local) and general vibration (vibration of workplaces). Vibration affecting individual parts of the worker's body is defined as local. The vibration of the workplace, which affects the entire body, is defined as general. In a production environment, local and general vibration is often encountered simultaneously, which is called mixed vibration.

According to the direction of action, vibration is subdivided into one acting along the axes of the orthogonal coordinate system X, Y, Z.

The general vibration according to the source of its occurrence is subdivided:

1. On the transport, which arises as a result of the movement of cars on the terrain and roads.

2. Transport and technological, which occurs during the operation of machines performing a technological operation in a stationary position and when moving through a specially prepared part of the production facility, industrial site.

3. Technological, which arises during the operation of stationary machines or is transferred to workplaces that do not have sources of vibration. Generators of technological vibration are equipment: sawmill, woodworking, for the production of technological chips, metalworking, forging and pressing, as well as compressors, pumping units, fans and other installations.

2 Impact of vibrations on the human body

The human body is considered as a combination of masses with elastic elements having natural frequencies, which for the shoulder girdle, hips and head relative to the supporting surface ("standing" position) are 4-6 Hz, the head relative to the shoulders ("sitting" position) - 25-30 Hz. For most internal organs, natural frequencies are in the range of 6-9 Hz. General vibration with a frequency of less than 0.7 Hz, defined as rolling, although unpleasant, does not lead to vibration sickness. The consequence of this vibration is motion sickness caused by disruption of the normal activity of the vestibular apparatus due to resonance phenomena.

When the vibration frequency of workplaces is close to the natural frequencies of internal organs, mechanical damage or even ruptures are possible. The systematic impact of general vibrations, characterized by a high level of vibration velocity, leads to vibration disease, which is characterized by disturbances in the physiological functions of the body associated with damage to the central nervous system. These disorders cause headaches, dizziness, sleep disturbances, decreased performance, deterioration in well-being, and cardiac dysfunctions.

The amplitude and frequency of vibration significantly affect the severity of the disease and, at certain values, cause vibration disease (Table 1).

Table 1 - Influence of vibration on the human body

The peculiarities of vibration impact are determined by the frequency spectrum and the location within its limits of the maximum levels of vibration energy. Local vibration of low intensity can have a beneficial effect on the human body, restore trophic changes, improve the functional state of the central nervous system, accelerate wound healing, etc.

With an increase in the intensity of vibrations and the duration of their impact, changes occur, leading in some cases to the development of occupational pathology - vibration disease.

Vibration refers to factors with high biological activity. The severity of response reactions is mainly due to the power of the energy impact and the biomechanical properties of the human body as a complex oscillatory system. The power of the oscillatory process in the contact zone and the time of this contact are the main parameters that determine the development of vibration pathologies, the structure of which depends on the frequency and amplitude of oscillations, the duration of exposure, the place of application and direction of the axis of the vibration effect, the damping properties of tissues, resonance phenomena and other conditions.

There is no linear relationship between the response of the body and the level of the impacting vibration. The reason for this phenomenon is seen in the resonance effect. With an increase in vibration frequencies of more than 0.7 Hz, resonant vibrations in human organs are possible. The resonance of the human body, of its individual organs occurs under the influence of external forces when the natural frequencies of vibrations of internal organs coincide with the frequencies of external forces. The resonance area for the head in a sitting position with vertical vibrations is located in the zone between 20 - 30 Hz, with horizontal vibrations - 1.5 - 2 Hz.

The resonance is of particular importance in relation to the organ of vision. The visual disturbance appears in the frequency range between 60 and 90 Hz, which corresponds to the resonance of the eyeballs. For organs located in the chest and abdominal cavity, the resonant frequencies are 3 - 3.5 Hz. For the whole body in a sitting position, resonance occurs at frequencies of 4 - 6 Hz.

Vibration pathology ranks second (after dust) among occupational diseases. Considering health disorders during vibration exposure, it should be noted that the frequency of diseases is determined by the dose, and the features of clinical manifestations are formed under the influence of the vibration spectrum. There are three types of vibration pathology from the effects of general, local and jerky vibrations.

When acting on the body general vibration the nervous system and analyzers primarily suffer: vestibular, visual, tactile. Vibration is a specific irritant for the vestibular analyzer, with linear accelerations for the otolith apparatus located in the vestibule sacs, and angular accelerations for the semicircular canals of the inner ear.

Dizziness, movement coordination disorder, motion sickness symptoms, vestibulo-vegetative instability were noted in workers of vibration professions. Impaired visual function is manifested by the narrowing and loss of certain areas of the visual fields, a decrease in visual acuity, sometimes up to 40%, subjectively - darkening in the eyes. Under the influence of general vibrations, there is a decrease in pain, tactile and vibration sensitivity. A jerky vibration is especially dangerous, causing microtrauma of various tissues with subsequent reactive changes. General low-frequency vibration affects metabolic processes, manifested by changes in carbohydrate, protein, enzymatic, vitamin and cholesterol metabolism, and blood biochemical parameters.

Vibration sickness from exposure to general vibrations and aftershocks are registered with transport drivers and operators of transport and technological machines and units, at factories of reinforced concrete products. For car drivers, tractor drivers, bulldozer drivers, excavator drivers exposed to low-frequency and jerky vibrations, changes in the lumbosacral spine are characteristic. Workers often complain of pain in the lower back, limbs, stomach, lack of appetite, insomnia, irritability, and rapid fatigue. In general, the picture of the effect of general low- and medium-frequency vibrations is expressed by general autonomic disorders with peripheral disorders, mainly in the limbs, a decrease in vascular tone and sensitivity.

The scourge of modern production, especially mechanical engineering, is local vibration... Mostly people working with hand-held power tools are exposed to local vibration. Local vibration causes spasms of the vessels of the hand, forearms, disrupting the supply of blood to the extremities. At the same time, vibrations act on nerve endings, muscle and bone tissues, cause a decrease in skin sensitivity, salt deposition in the joints of the fingers, deforming and reducing the mobility of the joints.

Oscillations of low frequencies cause a sharp decrease in capillary tone, and high frequencies cause vasospasm.

The timing of the development of peripheral disorders depends not so much on the level as on the dose (equivalent level) of vibration during the work shift. The time of continuous contact with vibration and the total time of exposure to vibration per shift are of primary importance. In molders, drillers, sharpeners, straighteners with a medium-frequency spectrum of vibrations, the disease develops after 8 - 10 years of work. Maintenance of a percussion instrument (riveting, stubbing) that generates vibration in the mid-frequency range (30 - 125 Hz) leads to the development of vascular, neuromuscular, osteoarticular and other disorders in 12 - 15 years. With local exposure to low-frequency vibration, especially with significant physical stress, workers complain of aching, breaking, pulling pains in the upper limbs, often at night. One of the persistent symptoms of local and general exposure is sensitivity disorder. Vibration, pain and temperature sensitivity suffers most sharply.

To factors of the working environment that aggravate the harmful vibration exposure on the body, include excessive muscle stress, unfavorable microclimatic conditions, especially low temperature, high-intensity noise, psychoemotional stress. Cooling and wetting hands significantly increases the risk of developing vibration disease by increasing vascular reactions. With the combined action of noise and vibration, a mutual enhancement of the effect is observed as a result of its summation, and possibly also potentiation.

Long-term systematic exposure vibrations leads to the development of vibration disease, which is included in the list of occupational diseases. This disease is diagnosed, as a rule, in industrial workers. In populated areas, vibration disease is not recorded, despite the presence of many sources of vibration (ground and underground transport, industrial sources, etc.). Persons exposed to environmental vibrations are more likely to suffer from cardiovascular and nervous diseases and usually present many general complaints of a somatic nature.

Maximum permissible level (MPL) vibration- this is the level of a factor that, during daily (except weekends) work, but not more than 40 hours per week during the entire working experience, should not cause diseases or deviations in health, detected by modern research methods during work or in long-term periods of life of the present and future generations. Compliance with the remote control vibration does not exclude health problems in hypersensitive persons.

In order to prevention adverse effects of local and general vibrations workers must use personal protective equipment. Personal protective equipment is subdivided into means:

For the operator's hands - gloves, gloves, liners, pads. (GOST 12.4.002-74 Personal protective equipment for hands from vibration. General technical requirements).

For the driver's feet - special shoes, soles, knee pads. (GOST 12.4.024-76. Special vibration protective footwear. General technical requirements. At enterprises with the participation of sanitary and epidemiological supervision of medical institutions, labor protection services, a specific set of medical and biological preventive measures should be developed, taking into account the nature of the impacting vibration and associated factors of the working environment.

" at"Vibration

At the present stage of technological progress, the fight against the adverse effects of vibration is acquiring more and more social and hygienic significance. This is caused, on the one hand, by the intensification of existing technological processes, on the other hand, by the increasing introduction of vibroactive technology in all sectors of the economy, and, first of all, manual machines, the fleet of which currently numbers millions of units.

The improvement of the technical and economic indicators of machines and equipment is carried out by increasing the power and operating speed while reducing the mass, which leads to an increase in the vibration activity of the machines.

Vibration as a factor in the working environment is found in the metalworking, mining, metallurgical, engineering, construction, aircraft and shipbuilding industries, in agriculture, transport and other sectors of the economy. Vibration processes are an active principle in compaction, pressing, vibration intensification, machining of materials, vibration drilling, loosening, cutting of rocks and pounds, vibration transport, etc. Vibration accompanies the work of mobile and stationary mechanisms and units, which are based on rotational or reciprocating motion.

Vibration are the vibrational motions of a system with elastic connections. By the method of transmission to the human operator, local and general vibrations are distinguished.

Y 14.1. Local vibration

Local vibration is one of the most common occupational factors. Its sources are hand-held machines (or hand-held power tools), controls for machines and equipment (handles, steering wheels, pedals), hand-held non-power tools and devices (for example, various hammers), as well as workpieces that workers hold in their hands. Working with this equipment is associated with the impact on the human body of vibration transmitted through the hands, feet or other parts of the body.

Local vibration is classified as follows featured:

on method of transmission, the human operator, while emitting vibrations transmitted through the hands, through the feet, as well as affecting other parts of the body (on the lower back, thigh, chest when using some vibration instruments, for example, perforators);

on timing characteristics- emit constant (uncharacteristic for local vibration) and non-constant vibrations, incl. pulse, consisting of one or more vibration impacts, each with a duration of less than 1 s;

on spectral characteristics - ranges with a predominance of maximum levels in the octave bands of 8-16 Hz (low-frequency), 31.5-63 Hz (mid-frequency) and 125-1000 Hz (high-frequency) are distinguished;

on direction of action - vibration acting along the axes of the orthogonal coordinate system X l, Y l, BL.

According to the type of drive, manual machines are divided into pneumatic, electric and gasoline-powered machines, and according to the principle of operation, into machines of rotary action (grinders, polishing machines, etc.), impact action with a reciprocating movement of the striker (chipping hammers, hammered, riveting and etc.), impact-rotary action (nutrunners), impact-rotary action (perforators, etc.), pressing action (scissors of various types).

Vibration parameters can vary significantly depending on the operating mode, the type of material being processed, as well as on the technical condition of the tool. It is customary to refer to vibrating sources (objects), when working with which vibrations occur, amounting to at least 20% of the remote control, which corresponds to 108 dB (4.0-10 "3 m / s) vibration velocity or 112 dB (4, 0-10 "1 m / s 2) vibration acceleration.

Vibration levels on the handles of powered and non-powered tools fluctuate, in most cases, in the range from 112-124 dB, but can reach 128-136 dB on some types of tools (assessed by the corrected level of vibration velocity), while the frequency range varies from 2 to 2000 Hz.

The normalized parameters of local vibration are:

frequency (spectral) characteristics - root-mean-square values ​​of vibration velocity or vibration acceleration in absolute units (in m / s or m / s 2, respectively) or their logarithmic levels (in dB), measured in octave bands of geometric mean frequencies in the range from 8 to 1000 Hz;

single-digit frequency-weighted metric- the corrected value of vibration velocity or vibration acceleration or their logarithmic level (integral estimate of the frequency of the normalized parameter);

integral assessment by the frequency of the normalized parameter, taking into account the time of exposure to vibration - the equivalent corrected value of the vibration velocity or vibration acceleration or their logarithmic level (the energy equivalent level of the normalized parameter).

For integral parameters - corrected and corrected equivalent vibration levels - the following maximum permissible values ​​have been set: when evaluated by vibration velocity - 2.0-10 "2 m / s (112 dB), by vibration acceleration - 2.0 m / s 2 (126 dB ).

The maximum permissible values ​​are established for the duration of vibration exposure for 480 minutes (8 hours) of a work shift. Limits quoted are based on local intermittent vibration. Impulse vibrations are currently not regulated either in our country or abroad.

Corrected vibration acceleration or velocity measurements require the use of appropriate bandpass and weight filters. The value of frequency correction is based on the fact that vibration at different frequencies affects the change in physiological parameters in different ways.

The corrected (in frequency) level is used to characterize vibration tools in terms of their vibration hazard. To assess the vibration load and the degree of harmfulness of working conditions working with vibration tools, the equivalent corrected vibration level is measured or calculated taking into account the duration of vibration exposure during the work shift. The spectral characteristics of vibration are used to predict the nature of health disorders and to select preventive measures for vibration disease.

In domestic literature, to characterize the vibration of hand-held machines, it is customary to use mainly units of logarithmic levels of vibration velocity (in dB), in foreign works, absolute units of vibration acceleration (in m / s 2) are used. The lack of a single criterion for assessing local vibration makes it difficult to compare the results of scientific research in the field of vibration effects.

Measurement and evaluation of vibration in accordance with domestic sanitary standards is carried out separately along three orthogonal directions-axes (X l, U l, 1 L), in this case, the value of the controlled parameter along the axis on which the maximum vibration value is recorded, with the indication of this axis, is taken as the vibration characteristic of a hand-held machine.

In the international standard ISO 5349-1 (2001) and the EU Directive 2002/44 / EC, establishing requirements for the measurement and assessment of vibrations transmitted to the hands, a new standardized indicator has been introduced - the total (or total) vibration value equal to the vector sum (corresponding to the root square of the sum of squares of vibration acceleration values ​​measured along three orthogonal axes), ajjy, for which the following criterion values for an exposure duration of 8 hours per work shift:

limit value, the value of which should not be exceeded 5 m / s 2;

the value requiring the adoption of protective measures (prophylaxis) - 2 m / s 2.

To obtain total vibration by the calculation method, the measured value of vibration along the axis, where it is maximum, must be multiplied by a factor from 1.0 to 1.7 (recommendations for choosing the factor are given in ISO 5349-2, 2001).

The indicated limit values ​​are based on the results of studies that made it possible to establish that the manifestations of the hand arm vibration syndrome (HAVS or vibration white finger, VWF) develop later in persons exposed to vibration with an equivalent total value of vibration acceleration A (8), which is less than 2 m / s 2, and are not recorded at values ​​of А ​​(8) less than 1 m / s 2. It is believed that increasing the vibration level by 2 times halves the safe work experience, i.e. accelerates the development of vibration disease by 2 times. However, the absence of epidemiological data, the results of long-term clinical observations and laboratory physiological and hygienic experimental studies in order to establish a dose-effective relationship between the parameter of the vector sum of vibration and changes in physiological parameters, makes the above limit values ​​not sufficiently reliable.

It is planned to switch to a system for measuring and evaluating local vibration based on full vibration acceleration in our country as well.

Risk factors. The effects of vibration and the likelihood of developing vibration disturbances depend on many production and non-production factors, called "Risk factors" including: characteristics of vibration impact, associated production factors, individual factors. Most significant factors are:

Frequency composition of vibration, level, impulse, total duration of exposure per shift, the presence of interruptions in work, including micropause;

physical load (weight on the hands in the process of working with a vibration tool, pressing forces and grip of the handles, working posture, the area and location of parts of the hands exposed to vibration), since vibration is transmitted to the human operator in the process of force interaction with the vibration tool, the area and location parts of the hands exposed to vibration;

Type and technical condition of equipment, tools and accessories, used material of handles and plug-in tools, thermal conductivity of the material;

Associated production factors that aggravate the effect of vibration and affect peripheral blood circulation (general and local cooling, blowing and wetting hands, noise, harmful chemicals);

individual factors affecting peripheral circulation, such as nicotine, certain drugs, past diseases that can affect blood circulation, as well as other individual characteristics (for example, the age of starting work in a vibration hazardous profession less than 18 years old and over 45 years old, morphoconstitutional criteria) ;

non-industrial exposure to vibration and cold (home activities with vibration instruments, hobbies).

The main criteria by which one can judge the degree of risk of exposure to a factor on the human body, are:

the frequency of specific violations;

the degree or severity of violations;

the timing of the development of violations (latency period).

Concomitant factors exacerbate the effect of vibration, accelerating the development of vibration disorders by 1.1-1.5 times; the most powerful of the above factors are the cooling microclimate, physical effort, noise and smoking.

Hygienic characteristics of the working conditions of the main vibration-hazardous professions. Those working with hand-held machines (hand-held mechanized vibration tools) are usually called operators, and the professions in which the risk of developing vibration disease is the highest are called “vibration-hazardous”.

The most “vibration-hazardous” occupations are those in which workers are exposed to high-intensity vibration in the most aggressive mid- and high-frequency ranges. These are professional groups of casting cutters, emery workers, fellers, sharpeners, grinders. In working in these professions, the latency period for the development of vibration disease is minimal (averaging 8-12 years), and the frequency of cases is the highest and can reach 30% (according to targeted clinical examinations). It should be noted that the prevalence and latency period of vibration disease in the same occupational groups of workers may differ significantly when analyzing various sources of information on morbidity - data from periodic medical examinations conducted by medical units of industrial enterprises (trade union centers), or data from targeted clinical examinations of occupational pathological clinics. ...

Until now, there is no consensus regarding the degree of harmfulness of impulse vibrations generated by non-mechanized hand tools - straightening hammers, mallets, etc. regarding the degree of harmfulness of impulse vibration effects. A significant part of the authors classifies them as the most harmful. However, a longer latent period of vibration sickness in groups of workers who are not exposed to impulse and non-constant vibrations of the same levels indicates that this issue has not yet been fully resolved. V tab. 14.1 the average values ​​of the latent period of development of vibration disease are presented in comparison with the average levels of vibration for the main vibration-hazardous professions.

The general hygienic characteristic of the working conditions of the most vibration-hazardous professional groups is the effect of high-intensity vibration with vibration speed levels of 124 dB or more, the frequency range of which is in the range of 63-250 Hz and above (medium and high-frequency vibration); these works are characterized by significant physical severity (due to the weight of the instruments) and are often carried out in conditions of general and local cooling. These factors together determine the development in a short time of the most characteristic syndrome of vibration disease - "white fingers". Later periods of development of vibration disease in some professional groups (for example, among molders) with significant levels of vibration of tools are due to the low-frequency spectrum of vibration, which mainly causes changes in the neuromuscular and osteoarticular apparatus, as well as the lack of significant physical effort and cooling.

Physiological mechanisms of vibration action. Human perception of vibration is a complex physiological and psychological process, in the implementation of which analyzers of somatic sensitivity are involved: cutaneous, proprioceptive, interoceptive, vestibular. In the skin analyzer, the transformation of mechanical energy into a nervous process occurs in mechanoreceptors; receptors of tendons, fascia and joints are also involved.

Basically, these are encapsulated receptors related to the primary sensory, i.e. those in which the substrate perceiving external influence is embedded in the sensory neuron itself. These include such receptor formations as Meissner's little bodies, Pacini's little bodies, hair follicles. The vibration sensation threshold is approximately 70 dB in terms of vibration velocity, i.e. well above the auditory threshold. The limits of response of the skin analyzer to the perception of mechanical vibrations are also significantly narrower. The interval between the threshold value and the value of the stimulus causing pain is about 70 dB for the skin analyzer. Experimental psycho-and neurophysiological studies indicate the presence of at least two independent systems of vibration perception: superficial, low-frequency, providing the perception and transmission of vibration with a frequency of 0.5 to 40 Hz, and deep, high-frequency, activated in the frequency range from 50 to 500 Hz. At the same time, Meissner's bodies are sensitive to low-frequency vibrations, and the fibers of the second system come from the deep tissues of the hand, presumably innervating Pacini's little bodies. The proprioceptive system is closely related to the vestibular analyzer.

At low frequencies (up to 10 Hz), oscillations, regardless of the place of their excitation, propagate with very little damping, involving the entire body, including the head, in the oscillatory movement. With an increase in the muscle tension of the arm, the conductivity of vibrations increases at all the studied vibration frequencies, reaching the highest value for frequencies of 30-60 Hz, corresponding to the frequency range of the natural vibrations of the arm.

The peculiarities of the mechanical properties of the human body and the functioning of sensory systems determine the unequal sensitivity of a person to vibrations of various frequencies. Workers who use hand-held machines for a long time have a variety of changes in the muscles of the shoulder girdle, arms, and hands. Under the influence of vibration, the electrical excitability and lability of the neuromuscular apparatus change, and these shifts often occur early, precede other subjective and objective changes and are distinguished by significant persistence even after the termination of contact with vibration.

The effect of vibration on the body causes various changes in the activity of the central and peripheral nervous systems. Particularly sensitive to the action of vibration are the sections of the sympathetic nervous system that regulate the tone of the peripheral vessels, as well as the sections of the peripheral nervous system associated with vibration and tactile sensations. When exposed to vibration, all types of skin sensitivity decrease, the speed of the impulse along the nerve worsens, and paresthesias develop.

The direction of vascular disorders is determined, first of all, by the frequency characteristics of vibration. It was found that the ability of capillaries to spasm is manifested when exposed to vibration above 35 Hz, while the frequency range 35-250 Hz is the most dangerous in relation to the development of vasospasm. When exposed to vibrations of low frequencies (below 35 Hz), a picture of capillary atony or their spastic-atonic state is mainly observed. Disturbances of peripheral hemodynamics under the action of local vibration depend on the place of its predominant application. Long-term exposure to low-frequency vibration is mainly responsible for the development of angiodystonic syndrome and musculoskeletal disorders, and high-frequency vibration mainly causes angiospasm and vegetative-sensory polyneuropathies. The peculiarities of the action of vibrations of different spectral compositions determine a differentiated approach to the appointment of preventive measures.

The study of the perception of vibrations at the level of the whole organism is carried out mainly with the help of psychophysiological methods. To assess the impact of local vibration on the human body, a set of methods is used, including an assessment of the state of the neuromuscular apparatus and peripheral hemodynamics, as well as auditory sensitivity. The most informative methods are pallesiometry (measurement of vibration sensitivity) at frequencies of 63, 125 and 250 Hz, algesimetry (measurement of pain sensitivity), thermometry of the skin of the hands with a cold test, rheovasography of the vessels of the hands, determination of static strength and endurance of the muscles of the hands. Changes in indicators of vibration and pain sensitivity are detected in 80-95% of those working in contact with high-frequency vibration.

The coal industry, non-ferrous metallurgy and mechanical engineering take the leading place in terms of the incidence of vibration disease. The share of vibration sickness in the overall structure of occupational diseases in these industries is 15-19%. The highest morbidity rates per 100,000 workers are recorded among the cutters - 5.4 cases of vibration sickness; drillers - 5.9; wood fellers - 4.0; sharpeners - 3.9; molders - 1.0. The same professional groups, which are the most widespread, make the main contribution to the professional structure of vibration sickness, in which the professional groups of cutters have the largest share - up to 64%. moulders - up to 11%, emery makers - up to 11%, etc. In some professional groups, women make up the majority of those with vibration disease: among sharpeners, 76%, among bar workers - 57%, among emery workers - 47%, among grinders - 36%.

Dose-effective dependences of the effect of local vibration. To assess the likelihood of vibration disturbances in workers from exposure to local vibration, the international standard ISO 5349-1 (2001) proposed a model for predicting vibration disturbances.

The dose-effective dependence model proposed in standard 5349-1 (2001) is based on the results of studies of workers who were exposed in the course of their professional activities to vibration levels up to 30 m / s 2 (reduced to 8-hour exposure) for various work experience - (up to 25 years). The development used data on year-round workers who worked with the same tool every day during the entire period of work. The criterion for the presence of vibration disorders was the appearance of a symptom of whitening of the fingers, which is the result of peripheral vascular disorders. This criterion is accepted as a basis, since it is the best studied, it can be easily quantified, the easiest to identify and is quite specific. It is also believed to be the earliest sign of vibration exposure.

In accordance with the established relationship, exposure to vibration with a level close to that proposed in this standard as the limit (4 m / s 2) will lead to the appearance of a symptom of whitening of fingers in 10% of workers after 8 years, and when exposed to vibration with a level of 26 m / s 2 - after 1 year.

This dependence does not allow predicting the risk of white finger syndrome caused by vibration for any particular worker, but can be used to determine the criterion for vibration exposure, intended as a guideline for deciding whether to take measures to reduce the risk of harm to health due to the action of local vibrations for professional groups.

The model for predicting the development of vibration disorders, developed by the Research Institute of Occupational Medicine of the Russian Academy of Medical Sciences, is based on the results of statistical processing of data on the incidence of vibration disease of the 1st degree among workers of machine-building enterprises located in the middle climatic zone of Russia.

The established dependence is expressed in the form of the formula:

In T = -20 In L + C p,

T - latent period of WB development, years;

L - equivalent corrected level of vibration velocity,

С р - coefficient depending on the frequency (or probability р) of the development of WB.

In accordance with the established relationship, the first reliable values ​​of the probability of vibration disturbances (more than 10%) are established for works associated with the impact of vibration with an equivalent level of vibration velocity of 115 dB for 20 years. The increase in the risk of vibration disturbances with experience when exposed to vibration of low levels occurs at a slow pace. With an increase in the level of vibration, the probability of illness increases rapidly, making up 12% when exposed to vibration with a level of 124 dB in the group with 5 years of work experience and 46% in the group with 25 years of experience. Exposure to vibration with an equivalent corrected level of 112 dB (at the level of the remote control) does not lead to the development of the disease during 32 years of work with a vibration-hazardous tool in 90% of workers, while the maximum allowable level (124 dB) will be safe for the same percentage working only for 4 years.

Comparison of the forecast results according to the ISO 5349-1 (2001) standard and according to domestic data showed that the differences in the probability of the development of violations are from 10 to 35 times. This is due to the use of various criteria for evaluating vibration disturbances and methodological approaches to research. In our country, the diagnosis of vibration disease is established on the basis of a complex of subjective and objective signs - complaints of the worker, indicators of vibration and pain sensitivity, temperature of the skin of the fingers, data of rheovasography and capillaroscopy of the vessels of the hands, the results of a cold test. A change in one of the indicators is not sufficient to establish a diagnosis. The ISO 5349-1 (2001) standard uses epidemiological data on the prevalence of only one sign of vibration disorders - the symptom of whitening of the fingers, and only in the two most vibration-hazardous professions - forest fellers and drillers. This contingent of workers is simultaneously exposed to the vibration of the cold, which contributes to the accelerated development of vibration disturbances. With this method of data collection, overdiagnosis of violations is possible.

The concept of professional risk makes it possible to take into account not only industrial, but also individual risk factors. This allows in the near future to go to the assessment of individual risk and the calculation of the critical length of service for each worker, taking into account the characteristics of his working conditions and individual risk factors. The principle of a comprehensive assessment of individual risk is the quantitative accounting of all influencing risk factors (industrial and individual) by multiplying the partial weight coefficients of risks, using as a basis the basic risk calculated according to the chosen model for predicting vibration disease.

Prevention measures adverse effects of vibration and related factors when working with vibration tools include technical, organizational and technical, administrative and medical and preventive measures.

Technical (constructive) measures to reduce vibration, noise, physical activity and other factors include the maximum reduction in the mass of the tool in order to reduce the physical severity of work (the use of polycomposite light materials, magnesium alloys), which reduces the risk of vibration disturbances. Handles should be heated if possible. Handles of vibration tools must have a vibration-insulating coating with a heat transfer coefficient of no more than 5-10 W / (m 2 -K), or must be entirely made of material with a thermal conductivity coefficient of no more than 0.5 WDmK). The design of vibrating tools should exclude the possibility of blowing the hands of workers with compressed air exhaust or exhaust gases and getting them into the breathing zone.

Organizational and technical measures include:

Time protection - work regimes that should ensure a general limitation of the time of exposure to vibration during a work shift; rational distribution of work with vibrating tools during the work shift (work regimes with the introduction of regularly repeated breaks); also limiting the duration of continuous one-time exposure to vibration, rational use of regulated breaks (in winter and transitional periods of the year, breaks should be simultaneously used to heat workers). Overtime work with vibrating tools is not recommended.

Collective protection measures(protection against hypothermia). When working in open areas during the cold season, it is necessary to equip rooms for heating, rest and shelter from adverse meteorological conditions. The air temperature in these rooms should be within 22-24 ° C. In the cold season, employees must be transported to the place of work in insulated vehicles. Hot meals should be provided for workers at lunchtime and other breaks.

Individual protection means(anti-vibration gloves, ear muffs or earbuds, warm special clothing; in case of watering and the cooling effect of water - waterproof clothing, gloves and shoes).

Administrative Risk Mitigation Measures the development of occupational diseases when working with vibration-hazardous tools imply the fulfillment by employers of their duties in relation to workers in vibration-hazardous professions (admission to work only serviceable and adjusted tools with vibration protection, with handles lined with heat-insulating materials, etc.; periodic monitoring of the levels of vibration, noise and other; development of work regimes; providing employees with effective means of individual and collective protection, sanitary facilities, preventive nutrition, etc.; training employees in the correct ways to work with vibration tools that reduce the risk of developing vibration disease; ensuring that employees undergo regular medical examinations, etc. etc.).

Medical and preventive measures include: conducting preliminary and periodic medical examinations; physiotherapy measures; vitamin prophylaxis; spa treatment, etc.

Vibrations are one of the problems of modern megacities. Moreover, their intensity is constantly increasing every year. Why is modern science so actively investigating this problem? Why has vibration measurement become mandatory in many organizations and factories? The fact is that vibration is a phenomenon that causes a number of occupational diseases, which gives doctors reason to raise questions about measures to eliminate it.

Vibration concept

Vibration is a complex oscillatory process that occurs over a wide frequency range. How does it arise? When transferring vibrational energy from a source to a solid. Usually vibration is understood to have a tangible effect on the human body. This refers to the frequency range from 1.6 to 1000 Hz. Sound and noise are closely related to the concept of vibration. They accompany this phenomenon at high rates of oscillatory motion.

What subject in school studies such a concept as vibration? This is a very important subject. Ensuring labor protection is one of the main problems of Russia, raised to the level of national security.

Sources of occurrence

Mechanical vibrations are phenomena that occur in almost all machine tools, machines and tools that have unbalanced or unbalanced rotating parts that perform reciprocating and shock movements. The list of such equipment includes stamping and forging hammers, pneumatic and electric hammers, as well as fans, compressors, pumping units and drives.

If vibrational movements of mechanical bodies are performed with a frequency in the range of up to 20 Hz, then they are perceived only as vibration. Sound appears at high frequencies. It is vibration with noise. In this case, perception is produced not only by the vestibular apparatus of a person, but also by his hearing organs.

Vibration classification

Oscillatory movements can be transmitted in various ways. So, there is a general vibration. This is an oscillatory process that is transmitted to the human body through various supporting surfaces. General vibration adversely affects the cardiovascular and nervous systems. In addition, it causes pathologies of the digestive tract and organs of movement.

In turn, the following are distinguished from the general vibration:
- transport, arising from the movement of cars on the road;
- transport and technical, the source of which are machines and mechanisms involved in the technological process;
- technical, arising during the operation of stationary equipment or transmitted to the areas where the operating personnel are located, where there are no sources of vibration.

There is also local vibration. These are oscillatory movements transmitted through the hands. If a person encounters such a vibration systematically, then he may develop neuritis with a simultaneous disability.

When examining workplaces, harmonic or sinusoidal vibration is highlighted. These are such oscillatory movements in which the values ​​of their main indicator change according to a sinusoidal law. This vibration is especially common in practice.

Oscillatory movements are also distinguished by their temporal characteristics. So there is a constant vibration. Its parameters in their frequency change no more than twofold during the observation period.

There is also a fickle vibration. It is characterized by a significant change in the main parameters (more than twice).

In the study of which subject, students are given the opportunity to become more familiar with such a phenomenon as vibration? This is BZD. It is taught in high school.

Vibration parameters

The following values ​​are used to characterize oscillatory movements:
- amplitude, showing the greatest deviation from the equilibrium position in meters;
- vibration frequency, determined in Hz;
- the number of oscillatory movements per second;
- the speed of vibrations;
- period of fluctuations;
- acceleration of vibrations.

Industrial vibration

Questions about reducing the level of oscillatory movements that negatively affect the human body are especially relevant at the stage of developing a technological process, which is impossible without operating machines, machines, etc. But, nevertheless, industrial vibration is a phenomenon that cannot be avoided in practice. It arises due to the presence of gaps, as well as surface contacts between individual mechanisms and parts. Vibration also occurs when equipment elements are unbalanced. Oscillatory movements often increase many times over due to resonance phenomena.

Vibration monitoring

To control and further reduce the level of vibration in production, special vibration measuring control and signal equipment is used. It allows you to maintain the performance of outdated equipment and increase the service life of new machines and mechanisms.

Everyone knows that the technological process of any industrial enterprise requires the participation of a large number of fans, electrical machines, etc. In order for the equipment not to stand idle, technical services must carry out its timely maintenance or overhaul. This is possible when monitoring the vibration level, which allows timely detection of:
- imbalance of the rotor;
- bearing wear;
- misalignment of gears and other malfunctions and deviations.

The vibration control equipment installed on the equipment issues warning signals in case of an emergency increase in the amplitude of the vibration.

Effects of vibration on human health

Oscillatory movements primarily cause pathologies of the nervous system, as well as the tactile, visual and vestibular apparatus. Professional motor vehicle drivers and machinists complain of ailments of the lumbosacral spine. These pathologies are the result of the systematic impact of shock and low-frequency vibration that occurs at their workplace.

Those to whom oscillatory movements of the equipment are transmitted during the technological cycle suffer from pain in the limbs, lower back and stomach, as well as from lack of appetite. They develop insomnia, fatigue and irritability. In general, the picture of the effect of general vibration on a person is expressed in autonomic disorders, accompanied by peripheral disorders in the limbs, a decrease in sensitivity and vascular tone.

Local exposure leads to vasospasm of the vessels of the forearms and hand. In this case, the limbs do not receive the required amount of blood. At the same time, local vibration affects bone and muscle tissue, as well as the nerve endings located in them. This leads to a decrease in the sensitivity of the skin, to the deposition of salts in the joints, to deformation and a decrease in the mobility of the fingers. It is worth mentioning that the oscillatory movements performed in the range sharply reduce the tone of the capillaries, and at high frequencies, vasospasm occurs.

Occasionally, a worker has a vibration in his ear. What is this phenomenon? The fact is that the frequency of vibrational movements transmitted from operating equipment is very different. However, in a single enterprise, there is a rather narrow range of such values. This leads to the appearance of this or that type of vibration, as well as the accompanying noise. So, sounds can be low, medium and high frequency.

When does vibration occur in the ear? What does this state characterize? The fact is that sometimes the equipment creates oscillatory movements that are on the same level with auditory perception. As a result, the noise is transmitted to the inner ear through the body of the worker and his bones.

In practice, the permissible vibration level is distinguished. These are its values ​​that do not have a negative effect on the human body. These parameters depend on many factors (on the exposure time, the purpose of the room, etc.) and are measured by the vibration amplitude, vibration velocity, vibration acceleration and frequency.

Most Dangerous Vibration Levels

Features of the negative impact of oscillatory movements on the human body are determined by the nature of their distribution with a combination of mass and elastic elements. In a standing person, these are the torso, pelvis and lower spine. In a chair sitting, the upper body and spine are negatively affected.

The effect of vibration on human health is determined by its frequency spectrum. Those manual mechanisms, the oscillatory movements of which are below 35 Hz, contribute to the appearance of negative changes in the joints and the musculoskeletal system.

The most dangerous vibrations are close to human organs. This range is from 6 to 10 Hz. Fluctuations of this frequency also negatively affect psychological health. This frequency could well be the cause of the deaths of many travelers in the Bermuda Triangle. At vibration values ​​from 6 to 10 Hz, people have a feeling of fear and danger. At the same time, sailors strive to leave their ship as soon as possible. Prolonged exposure to vibration can lead to the death of the crew. This phenomenon is dangerous for the functioning of both individual organs and the whole organism as a whole. It disrupts the central nervous system and metabolism.

Vibration with a large amplitude is very dangerous. It has a negative effect on bones and joints. With prolonged exposure and high intensity of vibrations, such a vibration provokes the development. This professional pathology, under certain conditions, turns into a cerebral form, which is almost impossible to cure.

Elimination of oscillatory movements

How to avoid vibration in the body? What kind of activities should these be that will help preserve human health? There are two main groups of such methods. The measures of the first of them are designed to reduce vibration directly at the source of its occurrence. Such actions, carried out at the design stage, provide for the use of silent equipment and the correct selection of its operating modes. During the construction and further operation of industrial buildings, these measures relate to measures for the use of technically sound equipment.

The second method to reduce vibration is to eliminate it along the path of propagation. For this, vibration isolation of equipment and air ducts is carried out, vibration isolation platforms are built, workplaces are equipped with special rugs and seats. In addition, vibration in the path of its propagation can be eliminated by performing a whole range of acoustic and architectural planning measures. Among them:
- location of vibration sources at the maximum distance from protected objects;
- Appropriate placement of equipment;
- the use of a vibration-insulated and rigid mounting scheme for the unit, etc.

Time protection

In order to preserve the health of a person working with manual mechanisms or equipment transmitting vibrational movements to the body, special modes of rest and work are being developed. So, there is a limitation of the time of contact with machines and mechanisms up to 1/3 of a shift. In this case, two or three breaks of 20-30 minutes are necessarily arranged. Moreover, free time from work during the shift is provided for a variety of physiotherapy procedures.

Such work regimes are developed for vibration-hazardous professions and are a kind of preventive measures aimed at preserving human health.

Numerical name vibration

When dealing with different people, each of us behaves in completely different ways. Moreover, all this depends on the attitude towards the interlocutor and on the current situation. We despise or respect, hate or love, we listen to their opinion, or we do not care at all.

If a person met on the path of life is restrained and laconic, then such behavior becomes characteristic of us. A merry fellow and a joker, on the contrary, will make you laugh and will certainly cheer you up. How to find out that individuality of a person, which is hidden in the depths of his soul? The vibration of the name will tell you a lot. What is it? Numerological addition of consonants of a name. Using this method, you can determine the nature of relatives and spouse, friends and any person, even without knowing the date when he was born. It is only necessary to know the 9 numerical vibrations corresponding to the name. With their help, you can pick up the key to the human soul and feel like a real magician. No wonder some people say that this is the vibration of my heart. Indeed, with the help of this method, a magical weapon appears in the hands of a person, which will benefit those who know its power of influence and its main meaning.

The letters of each person's name conceal three meanings of their individuality. This is a numerical vibration:
- vowels;
- consonants;
- the sum of all letters.

These numerical values, taken together, characterize the most important aspects of the personality.

There is also a sound vibration of the name, because life is a continuous movement. That is why it has its own vibration. Each name has its own vibration. Throughout life, its meaning is gradually transferred to the owner. Scientists believe that the lower threshold of such vibrations is at 35,000 vibrations per second, and the upper threshold is at 130,000 / s. Those people who have the highest rate are resistant to various kinds of infections. They also have high levels of moral attitudes.

Vibration is commonly understood to mean complex vibrations in mechanical systems. From a physical point of view, there is no fundamental difference between noise and vibration. The only difference is in perception: vibration is perceived by the vestibular apparatus and the organs of touch, and noise is perceived by the organs of hearing. Vibration is the process of propagation of mechanical vibrations in a solid. Vibrations of mechanical bodies with a frequency below 20 Hz are perceived as vibration, and with a frequency above 20 Hz - both as vibration and as sound.

It is customary to distinguish general and local vibration... General vibration affects the entire human body through the supporting surfaces - the seat, the floor; local vibration affects individual parts of the body.

Sources of vibrations: manual pneumatic tools, as well as various technological processes, mechanisms, machines and their working bodies (internal combustion engines, knock-out grates of foundries, molding, centrifugal machines, chipping hammers, rammers, forging and pressing equipment, grinding and polishing machines, hydro-sandblasting, shot blasting, vibration abrasive equipment, etc.).

The nature of the impact vibration per person depends on the range of vibration frequencies, direction of their action, duration of exposure, type of vibration. General vibration below 0.7 Hz (pitching) leads to motion sickness. Vibration with a frequency of 6-9 Hz (coincides with the vibration frequency of internal organs) can lead to tissue rupture and internal hemorrhages. Local vibration causes spasms of blood vessels, promotes the deposition of salts, with prolonged exposure it causes a chronic occupational disease - vibration disease. Both with general and local vibration, the activity of the central nervous system is disrupted.

The main specifications vibration: frequency f, (hertz), vibration velocity v (meter per second), vibration amplitude A (millimeter).

The absolute values ​​of vibration parameters vary over a wide range, therefore, the concept of the level of vibration velocity, measured in decibels, has been introduced:

L v = 20 lg (v / v 0) ,

where v 0 is the threshold value of vibration velocity, v 0 = 5 10 -8 m / s.

In accordance with GOST 12.1.012-90 SSBT “Vibration. General safety requirements " rationing vibration loading is carried out separately in each standard octave band, different for general and local vibrations. General vibration is normalized taking into account the properties of the source of its occurrence and is divided into vibration: transport, transport-technological and technological. The normalized parameters are the levels of vibration velocity in octave frequency bands (2, 4, 8, 16, 32, 63 Hz) or displacement amplitudes. Local vibration limits - in octave bands with geometric mean values ​​of 8, 16, 32, 63, 125, 250, 500, 1000 Hz.

Methods vibration reduction:

Reducing the level of vibration at the source itself by improving the designs of machines and processes;

Detuning from the resonance mode (by changing the mass or rigidity of the system, etc.);

Vibration damping (vibration absorption) - the use of structural materials with high internal friction, the application of a layer of elastic-viscous materials on vibrating surfaces that have large losses to internal friction (plastics, wood, rubber);

Vibration isolation by means of shock absorbers, i.e. introduction of an additional elastic connection into the oscillatory system;

Active vibration protection - the introduction of an additional energy source that provides feedback from the insulated object to the vibration isolation system;

Personal protective equipment (shoes, gloves, pads, anti-vibration belts, pillows, pads, vibration-damping mats, vibration-damping shoes);

Work and rest mode (no more than 2/3 of the work shift, the effect of vibration), breaks, annual medical examinations;

Social and hygienic measures.