These are devices for increasing the amplitude of the vibrational displacement of particles of the medium, that is, the intensity of ultrasound. Two types of concentrator are used: focusing (to create ultrasonic vibrations outside the concentrator) and rod ones. Focusing concentrators are shown in Figures 6.12 and 6.13.

A spherical shell, which oscillates at a resonance frequency throughout the thickness, can serve as a radiating element (Fig. 6.12). The shell is excited by piezoceramic platinums, which have the same resonant frequency and cover it completely in the form of a mosaic. The radiation of vibrations into a cavity with water and the descending spherical wave are focused at the base of the glass with the object under study. The cavity of the glass is separated from the contact medium by a sound-transparent film. A solid with low sound absorption can also be used as a contact medium (Fig. 6.13). Rod concentrator is a solid rod of variable cross-section or variable density, attached to the emitter with a wider end or a part with a higher density of material. The principle of operation is based on an increase in the amplitude of oscillations of the particles of the rod as a result of a decrease in its cross section or density according to the law of conservation of momentum. The greater the difference in diameters or densities of the opposite ends of the rod, the greater the increase in amplitude. Such concentrators operate at frequencies from 18 to 100 kHz at the resonant frequency, that is, their length must be a multiple of an integer number of half-waves. The maximum linear size of the wide end of the concentrator must be less than λ/2. The gain of the concentrator K is the ratio of the amplitude of the displacements (or velocities) at its narrow A 0 (V 0) and its wide A n (V n) ends.

Rod concentrators qualify:

· According to the shape of the longitudinal section (step, conical, exponential, catenoid, ampoule)

· According to the cross-sectional shape (round, wedge-shaped and others)

· By the number of series-connected half-wavelength resonant concentrators (one, two, and so on stepped)

Figure 6.14 shows the different types of half-wave concentrators, along with the distribution of displacement amplitudes A and voltage Δ. There are 2 modes of operation of concentrators: oscillatory mode in an unloaded state (standing wave mode), traveling wave mode under load on a completely absorbing active medium. The degree to which oscillations approach traveling or standing wave modes is determined by the traveling wave coefficient:

A 0 min – displacement amplitude in the nodal section

A 0 max – amplitude of displacements at the antinode of oscillations

A variable cross-sectional area of ​​the concentrator can be achieved by changing their internal profile (Fig. 6.15). Concentrators can be made of titanium alloys (minimal acoustic losses, high vibration amplitude, fatigue strength), however, the connection of titanium with magnetostrictive materials is difficult; more often, concentrators are made of steels 40X and 45. The connections of the oscillatory system units are made at deformation nodes or displacement antinodes, where mechanical voltages are minimal.

The connection of ferrite converters with the concentrator is adhesive. Piezoceramic transducers using linings and coupling bolts, in addition to oscillatory systems with longitudinal vibrations, systems with bending and torsional vibrations are used (Fig. 6.16). Piezoceramic torsional vibration transducers made of two semi-cylindrical piezoelements polarized into a circular one and connected together with glue can be used (Fig. 6.17). However, they do not provide high emitting power. To eliminate this, the designs shown in Figure 6.18 are used. Between the frequency-reducing pads (Fig. 6.18.a), piezoceramic rings made up of separate sections of piezoceramics and silver electrodes are secured with a bolt and nut (Fig. 6.18.b). Piezoceramics are polarized along the periphery as one whole.

Acoustic oscillatory systems are used for multi-directional transmission of ultrasonic energy, which convert vibrations in several directions or accumulate energy from several sources in one direction (Fig. 6.19-6.20).

When installing wire leads in SPP for power electronics, USS is mainly used. The main process parameters in this microwelding method are: the vibration amplitude of the working end of the tool, which depends on the electrical power of the converter and the design of the oscillating system; compression force of welded elements; duration of inclusion of ultrasonic vibrations (welding time).

The essence of the USS method is the occurrence of friction at the interface between the elements being connected, resulting in the destruction of oxide and adsorbed films, the formation of physical contact and the development of centers of setting between the parts being connected.

An ultrasonic concentrator is one of the main elements of oscillatory systems of microwelding installations. Concentrators are made in the form of rod systems with a smoothly varying cross-section, since the radiation area of ​​the converter is always significantly larger than the area of ​​the welded joint. The concentrator is connected to the transducer with the larger input section, and the ultrasonic instrument is attached to the smaller output section. The purpose of the concentrator is to transmit ultrasonic vibrations from the transducer to the ultrasonic instrument with the least losses and the greatest efficiency.

There are a large number of types of concentrators known in ultrasonic technology. The most widely used are the following: stepped, exponential, conical, catenoidal and “cylinder-catenoid” type concentrator. In oscillating systems of installations, conical concentrators are often used. This is explained by the fact that they are simple to calculate and manufacture. However, of the five concentrators listed above, the conical concentrator has the greatest losses due to internal friction, dissipates the most power, and therefore heats up more. The best stability is found in concentrators with the smallest ratio of input and output diameters for the same gain K y . It is also desirable that its “half-wave” length be minimal. For microwelding purposes, concentrators with 2

The concentrator material must have high fatigue strength, low losses, be easily soldered with hard solders, be easy to process and be relatively inexpensive.

Calculation of an ultrasonic concentrator comes down to determining its length, inlet and outlet sections, and the profile shape of its side surfaces. When calculating, the following assumptions are introduced: a) a plane wave propagates along the concentrator; b) the vibrations are harmonic in nature; c) the concentrator oscillates only along the center line; d) mechanical losses in the concentrator are small and linearly depend on the amplitude of vibrations (deformation).

Theoretical Gain K y the amplitude of oscillations of the exponential concentrator is determined from the expression

Where D0 And D 1– respectively, the diameters of the inlet and outlet sections of the concentrator, mm; N– the ratio of the diameter of the inlet section of the concentrator to the outlet.

The length of the hub is calculated by the formula

(2)

Where With– speed of propagation of ultrasonic vibrations in the concentrator material, mm/s; f– operating frequency, Hz.

Nodal plane position x 0(waveguide attachment points) is expressed by the relation

(3)

The shape of the profile generatrix of the catenoidal part of the concentrator is calculated using the equation

(4)

where is the shape coefficient of the generatrix; X– current coordinate along the length of the concentrator, mm.

In this work, a computer program has been developed for calculating the parameters of five types of ultrasonic concentrators: exponential, stepped, conical, catenoidal and “cylinder-catenoid” concentrator, implemented in the Pascal language (Turbo-Pascal-8.0 compiler). The initial data for calculations are: the diameters of the inlet and outlet sections ( D0 And D 1), operating frequency ( f) and the speed of propagation of ultrasonic vibrations in the concentrator material (s). The program allows you to calculate the length, position of the nodal plane, gain, as well as for exponential, catenoidal and “cylinder-catenoid” concentrators, the shape of the generatrix with a given step. The block diagram of the algorithm for calculating the exponential concentrator is shown in Fig. 6.9.

Calculation example. Calculate the parameters of a half-wave exponential concentrator if the operating frequency is given f= 66 kHz; inlet diameter D0= 18 mm, output D 1=6 mm; concentrator material – steel 30KhGSA (ultrasonic speed in the material With= 5.2·10 6 mm/s).

Using formula (1) we determine the gain of the concentrator.

Rice. 6.9. Block diagram of the algorithm for calculating the exponential concentrator

In accordance with expressions (2) and (3), the length of the concentrator , position of the nodal plane mm.

Equation (4) for calculating the shape of the concentrator profile takes the following form after substitutions:

Calculations using a computer program of the profile of the generatrix of an exponential concentrator with a step by parameter X, equal to 5 mm, are given in table. 6.1. According to the table. 6.1 the concentrator profile is designed.

Table 6.1. Hub profile calculation data

In table Table 6.2 shows the results of calculations of the parameters of various types of ultrasonic concentrators made of 30KhGSA steel (with D0= 18 mm; D 1= 6 mm; f= 66 kHz).

Table 6.2. Parameters of ultrasound concentrators

* l 1 And l 2– respectively, the length of the cylindrical and catenoidal parts of the concentrator.

To transmit ultrasonic vibrations from the transducer to the working tool or to the working environment, ultrasonic installations use concentrators and waveguides; the latter have a constant cross-sectional area and a cylindrical shape.

Waveguides are used when there is no need to amplify the oscillation amplitude of the converter. Hubs are speed transformers; they have a variable cross-sectional area, often cylindrical in shape. Thanks to this cross-section, they convert low-amplitude ultrasonic vibrations transmitted by the transducer and concentrated at its input end into higher-amplitude vibrations at the output end. The latter are communicated to the working body (tool) of the ultrasonic installation. The amplitude amplification occurs due to the difference in the areas of the input and output ends of the concentrator - the area of ​​the first (input) end of the concentrator is always greater than the area of ​​the second.

Waveguides and concentrators must be resonant, that is, their length must be a multiple of an integer number of half-waves (λ/2). Under this condition, the best opportunities are created for matching them with the power source, the oscillatory system as a whole and the mass attached to them (the working tool).

Rice. 14. Half-wavelength concentrators

In ultrasonic technological installations, concentrators of exponential (Fig. 14, a), conical (Fig. 14, b) and stepped shapes are most widely used. The latter are performed with a flange (Fig. 14, c) or without it (Fig. 14, d). There are also conical concentrators with a flange (for example, in a PMS-15A-18 type converter), as well as combined concentrators, in which the stages have different shapes.

Concentrators and waveguides can be an integral part of the oscillatory system or its replaceable element. In the first case, they are soldered directly to the converter. Replaceable concentrators are connected to the oscillating system (for example, to an adapter flange) via threads.

For concentrators, the cross-sectional area changes according to a certain pattern. Their main characteristic is the theoretical gain K, which shows how many times the amplitude of oscillations of its output end is greater than the amplitude at the input end. This coefficient depends on the ratio N of the diameters of the input D1 and output D2 ends of the concentrator: N=D1/D2.

The highest amplitude gain at the same value of N is provided by a stepped concentrator. He has K=N2. This explains the widespread use of step-type concentrators in various ultrasonic installations. In addition, these concentrators are simpler to manufacture than others, which is sometimes the most important condition for the successful use of ultrasonic processing. The calculation of a stepped concentrator is much simpler than that of other types of concentrators.

The value of the amplitude gain factor of the stepped concentrator is taken taking into account the prevention of the possibility of lateral vibrations, which is observed at large gain factors (K>8...10), as well as its strength data. In practice, the gain of a stepped concentrator is taken to be from four to six.

The resonant length of a stepped concentrator lр is determined from the expression lр=а/2=С/2f, where X is the wavelength in a rod of constant cross-section, cm; C - longitudinal wave speed (for steel C = 5100 m/s); f - resonant frequency, Hz.

The film has the ability to reliably adhere to the grains of the polishing material located on the polishing pad. When the polishing pad moves, the film is removed from the glass and a new film is formed.

Glass decomposition and film formation occurs in a fraction of a second. From a chemical point of view, polishing can be considered as the continuous removal of a film from glass and its immediate formation.

Polishing should be considered as a complex physical and chemical process of glass actuation.

Polishing of parts is carried out on a B1.M3.105.000 machine with an aqueous solution of optical polyrite.

Processing is performed at a grinding speed of 40 rpm.

The parts are fixed to the device using dental wax.

Polyrite is the main polishing powder used in the optical industry. It has a cinnamon color and its chemical composition is a mixture of oxides of rare earth elements. It mainly contains cerium oxide (at least 45%). Polyrite density is 5.8-6.2*103 kg/m3.

The problem of choosing the correct polishing pad is very important for successful polishing. The parameters of polishing pad materials include their relative hardness, the structure of the surface layer of the material, the presence of hairiness and its nature.

These parameters directly affect the performance of the process, the accuracy of the geometric parameters and the roughness of the polished surface. The higher the rigidity of the polishing pad, the less the recession of the abrasive grain under the influence of loads and the greater the pressure in the contact zone of the abrasive grain with the material of the part. This pressure can lead to an increase in the depth of penetration of the abrasive grain into the material of the part, which may be accompanied by a slight increase in process productivity with a simultaneous deterioration in the class of surface roughness and an increase in the depth of the damaged layer, and to the destruction of the abrasive grain, which can cause crater-like gouging out of the material of the part. Increasing the rigidity of the polishing pad material makes it possible to reduce the defects characteristic of polishing in the geometric parameters of glass - rolled edges and surface waviness.

Moleskin is used to polish parts. Its surface layer is made in the form of cells that well secure polyrite particles, which carry out micro-cutting of the surface of the part. The good wettability of this material with an abrasive suspension facilitates the periodic change of abrasive particles in the cells of the polishing pad.

Fig.26. Block diagram of the technological process of mechanical processing of a plate made of electrovacuum glass C40-1

Technological process of mechanical processing of Polycor . taking into account the use of ultrasonic milling, it is a set of sequential execution of the following operations:

Surface grinding.

Grinding of ceramic parts is carried out on a JE525 profile grinding machine with a straight profile diamond wheel, grain size 80/63; bakelite bond B1; concentration of diamond grains – 50%.

Bakelite bond allows you to grind very brittle materials. This is due to the greater elasticity of the bakelite binder compared to ceramic. Thanks to this elasticity, this bond somewhat reduces the impact load on the particles of the material being processed from the abrasive grains, i.e., it creates conditions for their smoother penetration into the material.

Ultrasonic.

The main shaping is carried out on an experimental installation with an ultrasonic tool with a diamond-containing layer of grain size 80/63 at a spindle speed of 2500 rpm, feed 0.7 mm/min and a frequency of 22 kHz. The parts are glued onto a plate of technological (window) glass with a mastic consisting of wax, rosin and paraffin. The tool diameter corresponds to the minimum diameter on the outer diameter. External and internal contours are cut out in one operation.

To clean glass parts after polishing, washing liquids are used, which can be divided into organic solvents and hot alkaline solutions.

Cleaning of parts from mastic residues and various contaminants is carried out sequentially in toluene, ammonia peroxide solution, followed by rinsing in a flow of ionized water. Next, the parts are cleaned and dried in isopropyl alcohol. Boiling in isopropyl alcohol dehydrates (removes moisture) and at the same time further cleanses. The parts are kept in air until the isopropyl alcohol evaporates completely.

Fig.27. Block diagram of the technological process of mechanical processing of Polycor.

6. Calculation of a stepped concentrator.

6.1. Ultrasonic concentrators and waveguides.

Concentrators and waveguides act as resonant length links that amplify and transmit ultrasound energy from the transducer to the working area - to the tool. Maximum amplitude of oscillations of transducers Coll" href="/text/category/koll/" rel="bookmark">ultrasonic concentrators (speed transformers) are used to oscillate the tool and match the transducer to the load. Rods or tubes of constant cross-section connecting the transducer or concentrator to the load , are called ultrasonic waveguides.

Depending on the type of vibration, concentrators and waveguides can be longitudinal, bending or transverse vibrations. Waveguides of other and more complex types of vibrations are also possible. Work is underway to create waveguides for multidirectional transmission of vibrations and oscillatory systems with various types of vibrations.

By combining several waveguides together, it is possible to obtain various options for multidirectional transmission of acoustic energy. Such systems can be used both for multidirectional transmission of oscillations from one converter, and as an accumulating system, when energy from several sources is transmitted in one direction. The waveguide for converting radial vibrations into longitudinal ones is a disk in which converters are mounted on the periphery; in this case, longitudinal vibrations occur at the ends of the cylinder connected to the disk.

6.2. Characteristics of Concentrators.

Focusing concentrators are usually made either in the form of mirror systems or in the form of so-called focusing ultrasonic emitters of spherical or cylindrical shape. The latter are most often made from piezoelectric ceramics and vibrate at a resonant frequency throughout the thickness. Cylindrical magnetostrictive emitters are also used. Focusing concentrators are used both in laboratory practice and in industry, mainly in installations for the technological application of ultrasound: ultrasonic cleaning, dispersion, aerosol production, etc. Up to 90% of all emitted sound energy is collected in the focal spot of focusing concentrators. Since for good focusing it is necessary that the size of the concentrators be large compared to the wavelength, this type of concentrators is used mainly in the region of high ultrasonic (105 Hz and above) frequencies. With their help, intensities of 103-104 W/cm2 are obtained. The diagram of the focusing spherical emitter is shown in Figure 28.

Rice. 28 − Diagram of a focusing spherical emitter made of piezoceramics, oscillating along the thickness

A waveguide concentrator (sometimes called a mechanical transformer) is a section of a non-uniform (tapering) waveguide, in which energy concentration occurs as a result of a reduction in cross-section. Resonant waveguide concentrators in the form of half-wavelength metal rods with a cross section that changes smoothly according to a certain law or in jumps have become widespread. Such concentrators can provide an amplitude gain of 10-15 times and make it possible to obtain in the frequency range ~104 Hz vibration amplitudes up to 50 microns. They are used in ultrasonic machining machines, ultrasonic welding installations, ultrasonic surgical instruments, etc. The diagram of waveguide acoustic concentrators is shown in Figure 29.

For ultrasonic processing, exponential conical and symmetrical stepped concentrators are most widely used. The method for calculating these concentrators given below makes it possible to obtain data for their design quite simply and with sufficient accuracy for practical use.

Initial data for calculating the concentrator:

D2 – diameter of the hole to be machined 14 mm

n – amplitude gain 5

f – resonant frequency of the converter Hz

6.3. Methods for attaching the instrument to the hub.

The best performance properties are achieved by instruments manufactured as a single unit with a concentrator.

However, due to wear and tear, such a tool has a limited service life. The number of parts produced by one tool depends on the material being processed, the nature of the operation, and the required processing accuracy.

https://pandia.ru/text/78/173/images/image128.png" width="244" height="25">

(according to Fig. T. for a machine power of 2.5 kW, we take 56 mm)

The optimal ratio between the diameters of the steps is determined from the experimental curves shown in Fig. 31.

2) The estimated length of the concentrator is determined (https://pandia.ru/text/78/173/images/image132.png" width="328" height="49">

Also, the estimated length of the concentrator can be determined from the experimental curves (Figure 31).

Sound velocities in various materials used for the manufacture of concentrators are given in Table 2.

table 2

3) The weight of the concentrator can be determined from the expression:

In Fig. 32. A stepped concentrator is presented for processing holes with a diameter of 29.6 mm with an amplitude gain factor n=5 and a resonant frequency f=19 kHz.

Rice. 32 stage hub

For stepped concentrators https://pandia.ru/text/78/173/images/image140.png" width="178" height="49">

where S1 and S2 are the cross-sectional areas of the large and small steps.

N – area coefficient.

7. Analysis of dangerous and harmful production factors.

The selected lighting parameters do not contradict the requirements of GOST 12.3.025-80, according to which in mechanical assembly shops the general lighting illumination must be at least 300 lux.

GOST 12.1.003 - 83 establishes maximum permissible conditions for constant noise in workplaces, under which the noise affecting a worker during an eight-hour working day does not cause harm to health. Normalization is carried out in octave frequency bands with geometric mean frequencies of 63, 125, 250, 500, 1000, 2000, 4000, 8000 Hz.

According to GOST 12.1.003, it should not exceed 85 dBA, at workplaces: in metalworking - 75...100 (high noise level), in CNC grinding - 80 dBA, in ultrasonic - 60 dBA.

Sources of noise and vibration in the designed workshop are:

Machine tools for metal processing (grinding, metalworking, ultrasonic);

To protect against noise and vibration, the following measures are provided to reduce noise and vibration levels:

Acoustic treatment of the room (installation of sound-absorbing screens, casings, installation of soundproofing fences);

Installation of noise suppressors in ventilation systems.

A significant reduction in noise is achieved by replacing rolling bearings with plain bearings (noise is reduced by 10 dBA), and metal parts with plastic parts.

Carrying out these measures will reduce the values ​​of noise levels and vibration velocity to values ​​​​not exceeding permissible values ​​(GOST 12.1.003, GOST 12.1.012).

In accordance with GOST 12.1.030, the designed workshop meets electrical safety requirements (all machines are grounded). There is no risk of electric shock.

8. Measures to ensure safe working conditions.

The main labor protection requirements for the product and technological process are:

– safety for humans;

– reliability and ease of use of the equipment used in this technological process.

Thus, the operation of an ultrasonic machine for dimensional processing must be accompanied by compliance with all safety requirements, determined by:

GOST 12.2.009-80 “System of occupational safety standards. "Metalworking machines"

GOST 12.3.024-80 “System of occupational safety standards. "Injury safety"

The main causes of injuries when working on machines can be:

– moving mechanisms of machine tools;

– sharp elements of the workpiece and devices for securing it;

– malfunction of hand tools;

– conductive parts of installations or parts of a machine that accidentally become energized;

– poor design of the machine operator’s workplace;

– poor lighting of the workplace;

For a worker who will work on this machine, labor protection requirements can be presented in the form of the following factors:

– microclimate parameters;

– industrial lighting;

– production noise;

– industrial vibrations;

9. Microclimate parameters.

The microclimate parameters accompanying the work activity of each participant in the technological process are:

– ambient temperature, t, °С;

– air speed, W, m/s;

Optimal and acceptable values ​​of these parameters are established for the entire working area of ​​the production premises, taking into account the time of year and the severity of the work performed.

In accordance with GOST 12.1.005-88, optimal microclimate parameters will be maintained in the workshop (Table 3).

Table 3 – Microclimate parameters

The specified microclimate parameters are supported by heating and ventilation systems.

In accordance with SN 245-71(88), with a specific volume of more than 40 m3/person, it is permitted to use a general ventilation system in production premises. To remove generated dust and coolant aerosols, local exhaust ventilation systems are provided.

To maintain the temperature in the room (especially in winter), the workshop is equipped with a water heating system and electric heaters with fans that create thermal curtains at the gates and entrance doors in winter.

10. Industrial lighting.

The workshop premises of the production building are provided with natural and artificial lighting.

Natural lighting - overhead (through lanterns) and two-way side (through side openings in the walls of the building).

Artificial lighting – combined, consisting of general and local lighting. General lighting is implemented using high-pressure mercury gas-discharge lamps of the DRL-400(700,1000) type. Local lighting is provided using 36 V incandescent lamps.

Industrial lighting in metalworking shops is standardized in accordance with SNiP 05.23.95.

In clarification for machine shops and precision metal-cutting machines, the following lighting standards can be given (Table 4):

For local lighting, lamps are used that are installed on the machine and adjusted so that the illumination of the working area is not lower than the established values.

Lamps used for local lighting must be equipped with light-proof reflectors with a protective angle of at least 30°.

Glass, window openings and skylights are cleaned at least twice a year.

10.1. Calculation of artificial illumination.

Workplace lighting is the most important factor in creating normal working conditions. Insufficient lighting in the workplace can cause rapid eye fatigue, loss of attention and, as a result, lead to a work injury.

The minimum illumination of the workplace must be at least Emin = 400 lux.

Determine the distance between the lamps:

where h= 5 m – lamp installation height above floor level.

Thus l=1.4*5=7m.

We determine the size of the workshop in which turning is carried out:

workshop size A = 8 m; B = 20 m.

room area S = A*B = 160m2

3. Determine the number of lamps in the workshop:

We accept n=12 pieces.

4. Determine the required luminous flux:

where: k=1.3 – lamp power reserve factor,

b=0.47 – lighting installation utilization factor,

z=0.9 – illumination unevenness coefficient,

Luminous flux of one lamp:

This amount of luminous flux is provided by a DRL type lamp with a power of 200 W with a luminous flux Fl = 4.3 * 103 lm.

1) Determine the actual illumination:

11. Environmental protection.

In the era of the modern scientific and technological revolution, the problem of disruption of the ecological balance, expressed in the deterioration of the quality of the environment as a result of pollution by industrial waste, has become extremely acute. Their constantly increasing number threatens the self-purifying function of the biosphere, disrupts the ecological balance, and ultimately threatens with adverse consequences for humans. Environmental pollution is associated with the consumption and production of electricity, agricultural production, the development of transport, the nuclear industry and other industries. Industrialized countries are already beginning to experience a shortage of clean water. Industry consumes more and more oxygen, and the release of carbon dioxide increases. Currently, human production activity has reached such a scale that it causes changes not only in individual biogeocenoses (steppe, meadow, field, forest, etc.), but also in a number of historically established processes within the entire biosphere.

During the production of LPT blades, all unfavorable and harmful substances are processed in accordance with labor protection requirements: liquid production waste, such as washing solution, from a washing machine, used coolant is transported to neutralization stations, solid waste metal shavings are delivered to metal waste collection points.

12. Air purification.

During grinding work, dust is released. Cyclones are most widely used for cleaning air from dust with particle sizes greater than 10 microns. Their design is simple and operation is uncomplicated, they have a relatively low hydraulic resistance (750-1000 Pa), and high economic indicators. Cyclones operate for a long time in a variety of environmental conditions at air temperatures up to 550 K.

Cyclones (Figure 22) are used to clean the air from dry, non-fibrous and non-coalescing dust. Dust separation in cyclones is based on the principle of centrifugal separation. Entering the cyclone tangentially through the inlet pipe /, the air flow acquires a rotational movement in a spiral and, descending to the bottom of the conical part of the body 3, exits through the central pipe 2. Under the influence of centrifugal forces, particles are thrown towards the wall of the cyclone and fall into the lower part of the cyclone, and from there into the dust collector 4.

Rice. 33 – Dust collector: Cyclone

12.1. Pollution and air purification of the working area

Metal processing is accompanied by the release of chips, water vapor, oil mists and emulsions.

Maximum permissible concentrations of some of the most common substances in the air of the working area (Table 5):

GOST 12.2.009-80 “System of occupational safety standards. “Metalworking machines. General safety requirements" provides a device for removing dust, small chips and harmful impurities on metalworking multi-purpose machines.

Table 5 - Maximum permissible concentration

GOST 12.3.025-80 “System of occupational safety standards. “Metal cutting processing. Safety requirements” for the process of metal processing using cutting fluids imposes the following requirements:

cutting fluids must have permission from the Ministry of Health;

absence of continuous or pitting corrosion when exposed to COTS on a sample with a roughness of Ra = 0.63 for 24 hours;

COTS supplied to the cutting zone by spraying must meet hygienic requirements;

Cleaning workplaces from chips and dust should prevent dust formation.

Ventilation is an organized and regulated air exchange that ensures the removal of air contaminated with industrial pollutants from the room. - mechanical. Types of ventilation due to natural conditions. Natural ventilation creates the necessary air exchange due to the difference in the density of warm and cold air inside the room and colder air outside, as well as due to the wind. The ventilation diagram for our site is shown in Figure 34.

Fig. 34 − Ventilation diagram of an industrial building.

There are channelless and channel aeration. The first is carried out using transoms (air inlet) and exhaust lanterns (air outlet); it is recommended in large rooms and in workshops with large excess heat. Channel aeration is usually installed in small rooms and consists of channels in the walls, and at the outlet of the channels, deflector devices are installed on the covers, creating draft when the wind blows on them. Natural ventilation is economical and easy to operate. Its disadvantages are that the air is not cleaned and heated upon entry, the removed air is also not cleaned and pollutes the atmosphere. Mechanical ventilation consists of air ducts and motion stimulators (mechanical fans or ejectors). Air exchange is carried out regardless of external meteorological conditions, while the incoming air can be heated or cooled, humidified or dehumidified. The exhaust air is purified. The supply ventilation system takes air through an air intake device, then the air passes through a heater, where the air is heated and humidified and is supplied by a fan through air ducts into the room through nozzles to regulate the air flow. Polluted air is forced out through doors, windows, lanterns, and cracks. Exhaust ventilation removes contaminated and overheated air through vents and purifiers, while fresh air enters through windows, doors and structural leaks.

Local ventilation ventilates the areas of direct release of harmful substances and it can also be supply or exhaust. Exhaust ventilation removes polluted air through air ducts; air is taken in through air intakes, which can be designed in the form of: Local suctions are installed directly at the places where harmful substances are emitted: at electric and gas welding workplaces, in the charging departments of battery shops, at galvanic baths. To improve the microclimate of a limited area of ​​the room, local supply ventilation is used in the form of an air shower, an air oasis - an area with clean cool air, or an air curtain. An air curtain is used to prevent cold outside air from entering a room. To do this, an air vent with a slot is installed in the lower part of the opening, from which warm air is supplied towards the flow of cold air at an angle of 30-45 degrees. at a speed of 10-15 m/sec.

It is advisable to use a pneumatic cyclone, shown in Figure 35, as an air purifier on site.

Rice. 35 – Pneumocyclone

Suspended particles are separated from the gas flow under the action of centrifugal and inertial forces. The dusty gas flow enters tangentially through the inlet pipe into the housing, where, due to guides, it is sequentially divided into separate flows with further centrifugal separation of dust. Coarse dust settles on the walls of the guides and housing and falls into the dust collection hopper.
Gases with fine dust, divided into separate streams, enter the socket blades, where they change direction by 180°. At this point, fine dust falls into the bottom of the outlet, and then into the dust hopper and dust collector. Purified gases exit the dust collector through the internal channel of the outlet through the outlet pipe.

13. Conclusion on the section.

Thus, an analysis of dangerous and harmful production factors arising in the ultrasonic dimensional processing area was carried out. A calculation of the local lighting necessary for safe work on an ultrasonic machine was carried out. Environmental protection measures were proposed aimed at protecting the work area from air pollution. The ultrasonic sizing process is waste-free and environmentally friendly.

14. General conclusion on the work.

Summing up the results of the thesis, we can say that the use of ultrasound allows not only to increase productivity and reduce tool wear, but also to process thinner-walled parts by reducing cutting forces Rz. In the process of ultrasonic processing, the likelihood of chipping and destruction of parts is also reduced. The parts for which the process was developed met the basic requirements for them. Namely: the presence of cracks in glass is unacceptable; there were none in any of the above experiments. On the end surfaces of the plates, individual chips with a length of no more than 1 mm were allowed, with an exit to the working surface of no more than 0.2 mm wide, and to the non-working surface no more than 0.3 mm wide. Average tool wear is 0.03% for the production of one part made of polycor and 0.035% for a part made of C-40 glass. The main shaping of the part must be achieved through the tool and ultrasonic milling operation. It was possible to reduce the number of operations for manufacturing a part, thereby reducing the time to manufacture a part by 25-30%. Currently, machine equipment of this type costs about 15 million rubles. The installation on which the experiments were carried out is estimated at a little more than 1.7 million.

Based on the experiments performed, a report was created and sent to the customer’s enterprise. In case of a positive result in terms of performance, reliability, and satisfaction of the quantity of suitable ones, a contract for 2 similar machines will be concluded. In addition to the enterprise indicated in the diploma, such equipment will also be of wide interest to other instrument production. The design of the head allows not only ultrasonic milling with a diamond tool, but also without it. This feature, coupled with a CNC system, can be used to produce parts of complex shapes, performing the function of conventional milling and engraving equipment.

15. List of references.

1., Sh. Shwegla: Ultrasonic processing of materials (1984, 282 pp.)

2. , : Ultrasonic processing of metals (1966, 157 p.)

3.: Ultrasound in mechanical engineering (1974, 282 pp.)

4. E. Kikuchi, ed. : Ultrasonic converters 423s.)

5.: Handbook of electrical and ultrasonic processing methods (1971, 543 pp.)

6. “Ultrasonic processing of materials” - M. “Mechanical Engineering”, 1980

7. “Technological processes of glass processing in the electrovacuum industry” - M. Central Research Institute “Electromechanics”, 1972