RU2387531C2 - Procedure for ultra-sonic impact machine treatment of body surfaces to correct defects and to strengthen working surfaces - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: at finish stage of production there is performed impact treatment of surface of screw-propeller with impact components freely travelling along their axis to transfer kinematic energy transforming into potential energy sufficient for deforming and contraction of surface and near-surface regions of screw-propeller. Also characteristics of fluidity relative to a body are changed by means of super-imposed application of micro-relief and macro-relief on surface of a body through excited ultra-sonic impact effect of a set of impact tools under random or controlled a-periodic mode. Notably, micro- and macro-relief correspond to surface vortex flow of fluid medium flowing round a body. Surface of a metal body has multitude of recesses formed due to excited ultra-sonic impact effect of a set of impact tools under random or controlled a-periodic mode and arranged according to possible intervals between surface vortex flows formed near surface of a body when fluid flows along a body.

EFFECT: upgraded durability of metal.

6 cl, 23 dwg

Description

The scope of the invention

The present invention relates to the creation of methods of ultrasonic impact machining of manufactured metal bodies of various configurations (forms), carried out to harden surfaces and to correct external and internal manufacturing defects and fatigue defects that occur during operation, as well as to the creation of appropriate devices, ultrasonic transducers and, in addition, it relates to the corresponding machined metal bodies.

More specifically, the present invention relates to the application of ultrasonic impact energy to various configurations of an external surface treatment zone of a metal product using sets driven by ultrasound of impact needles in the configuration of an ultrasonic transducer making relative movement to scan the external working surface of the body of the product, such like a propeller, bearing or other machine part, moreover having a small diameter, freely moving impact needles with give sufficient energy to modify the parameters and properties of the surface and deformation and compression punch receiving surface areas and the adjacent subsurface areas of a substantial depth.

BACKGROUND OF THE INVENTION

The basic technology for applying ultrasonic impact energy to the surface of polypropylene and thermoplastic materials for welding or riveting is disclosed in US Pat. No. 5,976,314. However, it does not disclose a system suitable for reprocessing machined metal products using ultrasonic impact machining, due to which metal the surface and the subsurface region below it are deformed, which allows you to control the surface texture and hardness of the product, as it happens in Compliant with the present invention.

The application of ultrasonic energy to metal welded joints is disclosed in US Patent No. 3274033, according to which a horn of a transducer generating ultrasonic vibrations is contacted directly with a weld between adjacent thin titanium alloy panels to process welding defects. However, this system with a converter horn cannot transmit sufficient power to the solid metal body of the product to effectively penetrate a considerable distance into the subsurface region to deform and compress the surface and adjacent subsurface regions and increase the strength of massive metal bodies such as cast iron bodies that are used in various instrumental applications for compression (with compression) interaction (collision) with mating surfaces.

Various special percussion instruments for ultrasonic processing of metal are already known, including hand-operated transducers designed for surface deformation and subsurface plasticization of open configurations and contours, such as cylinders, segments of surfaces of revolution and flat sheets, using direct mechanical contact of an ultrasonic vibrating head with a metal surface treatment area. Typical devices of this kind are described in the copyright certificates of the USSR, including: SU 1447646 A1; SU 1263510 A2; SU 1756125 A1; SU 1255405 A1; SU 1576283 A; SU 998104; SU 1214396; SU 1481044 and SU 1703417 A1. Such technical solutions are associated with direct mechanical contact between the head of the ultrasonic transducer, oscillating at a given ultrasonic frequency, and the treated surface of a metal object. The ultrasonic transducers disclosed herein typically comprise a single directly excited shock element combined with an exciting surface of an oscillator that vibrates at a periodic ultrasonic frequency and which is used to process welded structures to correct welding defects.

French Patent No. 2662180 describes a system for applying ultrasonic pulsed energy to create plastic surface deformation at welding sites to correct welding defects in plastic materials. However, this publication does not disclose satisfactory methods or systems for ultrasonic machining or the design of an ultrasonic transducer, or any design or methods that can successfully create and control ultrasonic energy intensity sufficient to solve the problem of ultrasonic impact machining, so as to deform as surface, and the subsurface structure to a significant depth, with various configurations of the working boundary surfaces it is massive metal bodies for compression interaction with mating surfaces.

Publications IIW XIII-1617-96 and IIW XIII-1609-95 describe hand tools for applying ultrasonic shock energy directly from the transducer head, oscillating at the shock resonant frequency of the master oscillator. These transducers are special-purpose transducers with single percussion needles adapted for the configuration of a system designed to perform special functional processing of defects in welded structures.

These previously known systems with ultrasonic transducers are not satisfactory tools, systems or methods for the reprocessing and machining of metal working boundary surfaces of various configurations used for friction compression contact and sliding contact, which is, for example, between the surfaces of a rotating bearing, in brake drums or wedges, as well as in the engine cylinders, in which the pistons reciprocate with as much as HAND, propellers and the like which are carried to surface deformation and subsurface structure, improve hardness and texture changes to increase the service life while increasing the compression load bearing workers.

As a rule, previously known systems with ultrasonic transducers do not allow obtaining sufficiently high and easily controlled impact power on working boundary surfaces in significant surface areas of a metal product in order to precisely control both surface hardness and texture, and the structure of an adjacent subsurface region to a significant working depth, exceeding the limits of normal wear and tear. Known systems produce bead-hitting, and shock systems with an ultrasonic transducer provide sufficient power in order to reach plastic deformation temperatures sufficient for deformation processing in a molten or plasticized state. However, in accordance with the present invention, sufficient ultrasonic impact power is obtained in order to effectively achieve the tensile strength of the body material and thereby modify the surface layer.

Thus, previously known systems and methods are not universal systems and methods with an ultrasonic transducer, which are suitable in size, power and control to perform such working functions as are desirable for the repair or manufacture of metal working boundary surfaces having compression interaction with mating surfaces . Previously known technical solutions also do not allow deformation with plasticization and compression of surface and adjacent subsurface regions to a sufficient depth, in particular, when machining various surface configurations of massive metal bodies in order to obtain specified final structures in both surface and subsurface regions of the processed metal product. High power ultrasonic transducers must also be of limited size in order to machine the inner cylindrical working surfaces of bearings, keyways, etc.

In addition, the ultrasonic transducer must have an ultrasonic impact nature, which allows machining of metal objects with various configurations of interacting surfaces to a great depth. For example, we consider the problems of manufacturing and / or repairing a propeller having critical surface characteristics for blades, hubs and fillets having various configurations and masses, as well as having various subsurface defects such as shells, corrosion, wear, cracks and welding stresses, which worsen the reaction of the working surfaces of the propeller blades during underwater compression and sliding interaction with sea water. Currently, successful multifunctional systems or methods for ultrasonic impact machining are not known under such various sets of conditions that are encountered in the manufacture and maintenance of marine propellers.

Typical known systems for the manufacture and repair of marine propellers are expensive and complex, and they include a number of incompatible processing methods, such as heat treatment of a metal product in an oven, creating defects that reduce the service life of the marine propeller. Propellers are usually obtained using the casting process, when there are subsurface pores, shells, cracks and geometric deviations from a given configuration. Manufacturing defects can be detected by ultrasonic, x-ray and other tests without destruction. Typically, repairs are carried out using cycles of heat treatment and controlled cooling, grinding, machining, surfacing, etc., which, in turn, introduces new mechanical stresses, creates fatigue and corrosion characteristics, and is also expensive and time consuming. In particular, heat treatment is critical in the presence of mating surfaces, variations in blade thickness, uneven distribution of masses, etc., which leads to an uneven distribution of thermal deformations and to unfavorable residual tensile stresses that accelerate corrosion and provoke destruction during operation due to fatigue and wear, especially when exposed to sea water.

It is also necessary to perform various types of surface treatment after internal heat treatment, for example, to apply protective coatings to the propeller blade and the like, which, in turn, introduces surface defects that disrupt the functioning of the working surface. For example, the required surface characteristics can range from optical surface smoothness to a predetermined degree of surface roughness needed to adhere to the outer finish layer. Currently unknown methods or systems of ultrasonic machining that can provide these conditions.

Thus, it is relevant to provide ultrasonic machining of the working boundary surfaces of the product, which allows to achieve the specified surface smoothness, hardness, surface deformation, surface relief, compressive stresses, frictional resistance, reflectivity and corrosion resistance, and allowing correction of surface and subsurface defects.

In accordance with the stated first objective of the present invention is the creation of new methods, transducers and systems for multifunctional ultrasonic impact machining, allowing restructuring of the working surfaces of metal products of various configurations during manufacture or repair.

An accompanying object of the present invention is the processing of metal products at the final stage of manufacturing operations by replacing the difficult and expensive heat treatment operations in the furnace by processing using ultrasonic shock energy at the surface of the product, carried out at ambient temperature, and preparing, using an improved conversion matrix, the surfaces of the metal products, having various surface configurations for manufacturing operations in which the rear These modifications of the surface texture and related sub-surface areas introduced after the usual procedures for the manufacture of metal products, such as grinding, surfacing, alloying and applying protective coatings, etc.

Another objective of the present invention is the use of tools, systems and methods for ultrasonic impact surface and subsurface plastic deformation, which allows to increase the surface strength of a metal product, while reducing complexity and cost of manufacture.

Improving the reliability of the propeller using ultrasonic impact machining is achieved by sending aperiodic power pulses to the surface of the product with the help of free axial movement of impact needle elements driven by the primary surface of the transmission of ultrasonic energy vibrating at a given ultrasonic frequency.

Critical in such operations is the creation of sufficient power to deform the surface and subsurface areas of the product to the required depth. The present invention allows to significantly increase the output power through the use of a transducer excited from a periodic ultrasonic frequency energy source, and groups of energy concentration steps operating at conjugate higher harmonic resonant frequencies, with an increase in the quality factor and with significantly higher speeds communicated by needle impact elements, making free axial movement.

SUMMARY OF THE INVENTION

New methods and systems of ultrasonic impact machine tools allow the processing of the correct shape, flat and irregularly shaped working surfaces of a metal product, due to the application of ultrasonic impact energy from needle-shaped impact elements having a high speed and small diameter to the treated surfaces. Due to this, critical working surface and adjacent subsurface areas of metal products, including propellers, are plastically deformed with the creation of specified surface textures and increased hardness and with associated subsurface structural transformations caused by surface impact. The ultrasonic transducer has a periodically oscillating surface of energy transfer to a set of small diameter impact needles that have free axial movement and collide with the machined surface at high speed, resulting in a sufficiently high energy being released to deform the product to a greater depth than was previously achieved. Impact needles of the set, which are individually driven from the oscillating surface of the transducer operating at a single given ultrasonic frequency, collide with the working surface, transmitting kinetic energy to it, and bounce in an aperiodic controlled mode or randomly.

The impact power of small-diameter needles that move independently of the excitation transducer to the product in the free axial motion mode allows very high speeds and high energy to be obtained from a source of periodic ultrasonic power. This leads to sufficient shock power for both plastic surface and sub-surface structural reconfiguration of heavy metal objects to a significant depth. Due to the small impact region, short impact time, cyclic load curve and heat absorption characteristics of the metal product, the product quickly heats and cools during ultrasonic impacts in a localized area at the impact point and undergoes machining at ambient temperatures, and the product remains after machining at ambient temperature.

The transducer is coupled with the product due to the work of sets of impact needles, which bounce from the working surface to the excitation surface, which performs periodic ultrasonic vibrations. This allows you to get a broadband pairing performance that maximizes the output working power transmitted using separate needles with a very high speed, instantly colliding with the surface, from a power source of periodic ultrasonic vibrations, in accordance with the expression for the kinetic energy of impact (W = mv ² / 2) used in the present invention. Thus, the kinetic energy obtained from free-flying high-speed impact needles, which is a function of v ² , is much greater than that which can be obtained by directly impacting the horn of the transducer into the product in accordance with the aforementioned US Patent No. 3274033.

A multiple increase in the speed of vibration of shock needles at the time of impact is caused by a nonlinear relationship between the speed of oscillations and the gap between the end of the needle and the shock (exciting) surface of the transducer head. In this case, the mass "m", which determines the impact energy at a certain speed, first of all includes the mass of the transducer and the mass of the needle, reduced to the end of the needle.

Moreover, the impact includes ultrasonic vibrations of the impact needle in the processed surface layer of the material, together with ultrasonic vibrations of the impact surface of the transducer head during individual ultrasonic impacts. Such ultrasonic vibrations, in turn, initiate the propagation of powerful ultrasonic waves in the processed material, which create individual effects of reducing the deformation resistance and relaxation in the processed material.

Thus, the depth of ultrasonic impact processing in this case is determined by the energy of the controlled ultrasonic impacts, ultrasonic deformations and ultrasonic waves, which are initiated in the product during the interaction of the ultrasonic transducer, impact needle and product.

Critical for the output power output are groups of mechanically interconnected successive stages in the working unit of the transducer, which is small in size to provide portability and the ability to carry out manual operations, so that it is possible to work in confined spaces, which provide high efficiency of power transmission from a basic source of periodic ultrasonic power . The groups of mechanically interconnected stages of the transducer have corresponding mechanical resonances harmonically associated with the primary frequency of ultrasonic vibrations, so that the much higher harmonic of this primary ultrasonic frequency allows you to give a very high speed to freely moving shock needles and to further increase the quality factor of the oscillation system, which helps to increase the output power, received from the available input power generator. In addition, to efficiently transfer power from the corresponding operating stages of the transducer, consistent instantaneous resistances are ensured at the instantaneous instant operating moment, when the impact needle elements, which make free axial motion and are driven by the vibrating transducer surface vibrating at the primary ultrasonic frequency, collide aperiodically with product surface.

This mode of operation allows a new heat treatment of the product to plasticize the surface and subsurface metal with an increase due to impact machining of the working surface strength of the product and its operational characteristics in the presence of compressive forces. Thus, thermal machining in the plastic state, when compressed by the impact forces of the surface layer of the metal of the product (for example, a propeller), creates an increased compression working force that can compensate for the costs of the compression interaction with sea water of mechanical surfaces, for example the surfaces of the propeller blades , which leads to increased operational durability.

A scanning system using a lathe mechanism, a surface scanning system, or another system is designed to systematically scan the movable head of the transducer in accordance with a predetermined scanning pattern (pattern), as a result of which individual impacts from impact elements are uniformly and in any given way distributed over selected surface product zones, which may have different interconnected surface configurations for individual products.

Thus, in accordance with the present invention, new ultrasonic vibrating elements and methods of operation are provided, as well as new types of ultrasonic impact machining, for machining the interacting working surfaces of various metal products to produce plastic surface and subsurface deformation, resulting in structural changes and increasing hardness of material and service life.

The foregoing and other characteristics and advantages of the invention will be more apparent from the following detailed description, given by way of example, not of a limiting nature and given with reference to the accompanying drawings.

Brief Description of the Drawings

In the accompanying drawings, like elements have the same reference numerals to facilitate comparison.

Figure 1 shows a block diagram of a system for ultrasonic impact machine tool surface treatment in accordance with the present invention.

Figure 2 schematically shows how the compressive stresses are excited in the working surface and in the subsurface region immediately below it, in response to a shock from a set of shock elements.

Figure 3 schematically shows the excitation of ultrasonic shocks using a freely flying shock element, which receives on one side (asymmetrically) the shock energy of the excitation due to the stop (collision) in the oscillating head of the ultrasonic transducer, as a result of which the shock element begins to move at high speed as a freely moving object and collides with a work surface undergoing ultrasonic machining.

Figure 4 schematically shows the construction of a block of a typical magnetostrictive ultrasonic shock transducer, which interacts with the outer working surface of a metal product.

Figure 5 schematically shows the cross section of a multi-stage transducer, ending with a set of shock elements that can make free axial movement at high speed, with a blow to the surface of the product, in the report on periodic impacts of the boundary (exciting) surface of the transducer.

Figure 6 schematically shows the impact interaction of freely moving needle impact elements of a typical set with a periodically vibrating excitation surface of the transducer, as a result of which they receive vibrational energy for its transfer upon impact to the product surface in a controlled and random aperiodic mode of operation.

Fig. 7 schematically shows a cross-section of the surface of an article scanned by impact needles and deformable when in the plastic state by the impact tips of the needles during direct contact with the head of an ultrasonic impact transducer and after impacting the head of the transducer into a needle in accordance with the present invention, in the process of plastic deformation and restructuring of the surface of the product.

On Fig schematically shows a scanning mechanism for moving the ultrasonic transducer and its set of percussion elements over a selected area of the product, so as to create a uniform pattern (impacts) on the surface (heat treatment of the product is not shown).

On figa-9E shows a set of typical products having work surfaces with various surface configurations for applying compression forces to mating surfaces that require ultrasonic impact machining in accordance with the present invention, to increase the permissible work load and correct manufacturing defects.

Figure 10 schematically shows a section of a product of a propeller blade undergoing ultrasonic machining in accordance with the present invention.

11 schematically shows a cross section of the propeller blade, where you can see the area subject to ultrasonic plastic impact deformation to correct manufacturing or operating defects, in accordance with the present invention.

On Fig schematically shows the dependence of the strength of the material of the body of the product from operating temperatures.

13 schematically shows a typical stress versus load curve for stress-tested metal components.

On Fig schematically shows the different levels of deformation introduced into the working surface of the product due to the process of ultrasonic machining in accordance with the present invention. Two mating surfaces of the working bodies are shown, the upper body being processed to a certain depth by means of ultrasonic shocks and has zones I, II and III (in accordance with FIG. 13), while the lower body was not processed.

On Fig schematically shows the effect of elements in the form of impact needles on the working surface of the product during the machining process in accordance with the present invention.

On Fig shows the flow of fluid from (flowing past) a smooth surface, such as the surface of the propeller.

On Fig shows a graph of the dependence of the flow velocity of a medium on a smooth surface on the distance to the surface.

On Fig shows a graph of the dependence of the distance between local surface vortex flows at the surface of the flow velocity.

On Fig shows a graph of the dependence of the intensity of cavitation erosion on the distance between the local surface vortex flows at the surface.

On Fig shows a graph of the effect of flow velocity near the surface on the intensity of cavitation erosion.

On Fig shows the effect of changes in macrorelief on the shape of the current relative to the surface of the propeller after ultrasonic impact machining.

On Fig shows the effect of changes in the microrelief on the shape of the current relative to the surface of the propeller after ultrasonic impact machining.

On Fig shows a top view where you can see the flow of fluid relative to the surface after its ultrasonic impact machining, taking into account the impact of the modified surface profile and the micro- and macrorelief of the surface on the flow shape.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

We now turn to the consideration of figure 1, which shows a block diagram of a system for ultrasonic impact machining of surfaces of a metal product, shown as a working surface 13, through the use of a set of ultrasound-moved impact elements 12, usually containing three or four spaced apart another element designed to collide with the working surface 13 under the control of the head 11 of the ultrasonic transducer. The source 10 of periodic pulsed energy, which usually operates at ultrasonic frequencies up to 100 kHz and excites oscillations in the transducer head 11, mainly operates using a frequency and phase feedback control circuit 14 that processes the feedback signal from the transducer head 11 to facilitate matching resonant characteristics of the head when exposed to the working surface 13, as shown more specifically in related applications.

Figure 2 shows a set 12 'of impact elements acting on the working surface 13 and penetrating into the subsurface region 17 of the body 15 of the metal product, and plasticizing the metal allows the surface texture to be processed and the subsurface structural modifications to be retained (stored) in the material of the body 15. This the impact is schematically shown in the subsurface region 17 as separate working areas for a set 12 'of three impact elements, deforming the subsurface metal to a depth that is determined is Busy shock capacity of individual impact elements in the set 12 '. The resulting deformation, typically representing a distribution of compressive stresses, spreads over the entire machined surface of the product by appropriate scanning of the transducer over the selected surface of the product, due to the scanning mechanism, such as a lathe mechanism or a scanning mechanism of the type described below, shown in Fig. 8.

The scanning device 20 shown in Fig. 8 comprises a universal joint type mechanism as a support for the transducer with a set of impact elements 12 intended for strong contact and regular scanning of the surface treatment zone 21 of a two- or three-dimensional product. The feed heads of the impact elements 12 supply the required impact energy from a set of individual impact elements for increments of the plastic deformation of the metal product, which are combined into a picture of a mainly homogeneous ultrasonic impact machining over the entire scanning area and allow you to get a given combination of the provided internal residual deformations, typically representing compressed a subsurface metal reinforcing the metal to carry out its working function of conjugation at rotating work surface and create the desired characteristics of the surface texture finish. Specialists can automate the scanning procedure and create selected scanning schemes depending on the configuration of the product or the functional operation when paired with the appropriate work surface or environment.

It was shown that at ultrasonic frequencies up to 100 kHz, when scanning with a set of 12 shock elements of the working surface 13, at corresponding scanning speeds, mainly uniformly compressed surface structures and textures can be induced throughout the scanned processing zone 21 (see Fig. 8) moreover, the subsurface metal will be compressed to a depth that exceeds the maximum expected wear of the workpiece. During this process, ultrasonic shocks lead to the instantaneous occurrence of high temperature, with the effect of rapid heating and cooling at the point of impact of each of the individual shock elements, which plastically deforms the surface and creates a surface texture and a subsurface compression layer that is uniformly hardened in place, throughout the working surface of the product, as the scan progresses, due to which the distribution of shock energy occurs over the entire working surface of the product and processing of the product in its plate stasified condition. This shock machining zone 21 is characterized by residual compressive stresses at the surface and in the adjacent subsurface region, which can be easily controlled to match the performance of various products or product areas, by choosing the energy and frequency of oscillation, characteristics of the shock cycle, mass and speed of the needle, and the like, whereby a predetermined surface texture and subsurface deformation are obtained, typically during secondary processing of castings and previously traditionally processed metal products, at the final stages of manufacturing and repair or maintenance, carried out during the working life of the products.

In order to achieve mainly greater energy transfer from the transducer 11 to the working surface 13 and to control or randomize the time of impacts of the individual impact elements 12 to the working surface 13, in accordance with the present invention, a free axial movement mode with free-moving axial impact elements 12 ″ in in accordance with figure 3. In this case, the free-flying impact element 12 ”, due to the abutment against the impact surface 18 of the transducer head 11, which performs ultrasonic vibrations, receives impact and acquires kinetic energy, whereby the impact element 12” begins to move at high speed in the direction of the working surface 13 as a freely flying element, to convert its kinetic energy on the working surface 13, as a result of which enough energy is released on the working surface 13 for texturing and compression of this surface and are adjacent x subsurface areas, while the metal product is in its plastic state. The impact element, after transferring its energy to the working surface 13 of the product, bounces off the working surface 13 to conduct the next shock cycle and receive energy from the impact surface 18 of the transducer head. This leads to controlled or random aperiodic impacts of the free-flying impact element 12 ”, which correspond to the aperiodic surface characteristics of the product, since the impact element 12” bounces and contacts the impact surface 18 of the transducer head in various phases during periodic oscillations of the transducer 11.

As discussed below with reference to Fig.6, the transducer and its set of freely moving along the axis of the impact needles, individually driven from the exciting surface of the transducer periodically vibrating at the ultrasonic frequency, creates a greater kinetic energy of the needle than the previously known transducers, and transfers power to an independent impact element 12 ”randomly and aperiodically from the product excitation surface periodically vibrating at the ultrasonic frequency.

A multiple increase in the speed of oscillation of shock needles at the time of impact is caused by a nonlinear relationship between the speed of oscillation and the gap between the end of the needle 12 and the head of the transducer 11. In this case, the mass "m", which determines the impact energy at a certain speed, includes primarily the mass of the transducer 11 and the mass of the needle 12, reduced to the end face of the needle.

Moreover, the impact includes ultrasonic vibrations of the impact needle 12 in the surface layer of the processed material 13, together with the head 11 of the ultrasonic transducer, during an individual ultrasonic impact. Such ultrasonic vibrations, in turn, initiate the propagation of powerful ultrasonic waves in the processed material, which creates individual effects of reducing the deformation resistance and relaxation in the processed material.

Thus, the depth of ultrasonic impact machining in this case is determined by the energy of controlled ultrasonic shocks, ultrasonic deformations and ultrasonic waves that are excited in the product during periodically controlled or accidental contact of the ultrasonic transducer 11, impact needle 12 and product 13.

Thus, this method of processing a metal work surface 13 allows the processing of work surfaces with various configurations, masses and surface characteristics using the head 11 of an ultrasonic transducer equipped with a set of 12 ”ultrasonic impact elements that collide with the product at locations on the external surface, in As a result, ultrasonic impact machine processing of the surface is efficiently performed due to surface deformation and adjacent sub surface area, which allows you to obtain the specified characteristics of the surface and the subsurface region, including compaction (compression) of the product material to obtain higher hardness and increase the expected service life, to give the working surfaces of the product surface resistance, contact characteristics with the medium and wear characteristics that encountered when working under specified operating conditions, collisions of mating surfaces in a compressed state.

Figure 4 shows a plan view of the configuration of the transducer, facing down to the product 25 of a three-dimensional configuration, which usually has a polished or machined surface texture and is held in a suitable mechanical holder 26. The portable and axis-free transducer 27 oscillates at a given ultrasonic frequency for account of a remote oscillation energy source (source 10 in FIG. 1), using a magnetostrictive transducer 28 with an excitation winding 29, forming the first sequential operating Stage I. Intermediate stage II is mainly a replaceable waveguide 30 for the concentration of oscillations of the incoming ultrasonic energy of a given frequency, for colliding and driving the indenter (pressed) element (s) 31 of the third stage III, which, in turn, plasticizes and compresses ultrasonic metal product 25 (stage IV). The preferred indenter element (s) is a set of needles operating in the mode shown in figure 3, which provides a sufficiently high speed of impact energy to control the structure of the subsurface region of the product at sufficiently large depths to improve the output strength of the specific processed products.

Thus, in accordance with the present invention, there is provided a multi-stage transducer matrix, which ends with a striking head driven by a stage of transmitting power of a transducer performing ultrasonic vibrations by means of an intermediate waveguide conversion stage into which it abuts. The elements of the striking stage are mainly a set of impact elements performing free axial movement, which individually randomly and in a controlled aperiodic mode convert instantaneous periodic energy received from the ultrasonic energy excitation system into the movement of individual impact elements in the set, which, when they collide with the surface products betray him their energy received from the power source of oscillation of the transducer. These shock elements then bounce off and allow the transducer to perform the next beat of shock energy transfer due to the stop (s) in the intermediate exciting surface of the energy transducer that performs periodic oscillations in a random or controlled phase of its oscillation cycle. Taking into account the different course of movement of the percussion needle elements of the set making free movement along the axis between the intermediate exciting surface of the energy converter and the surface of the product, in different phases of oscillations, depending on the topology of the surface of the product, individual set of shock needles act independently and not periodically at the same time (not in unison ) to transfer the transferred energy from the shock elements to the surface of the product.

The efficiency of the transducer devices shown in FIGS. 4 and 5, and the methods of their use to obtain the energy necessary to plasticize and compress metal products, depend on the effective and coordinated coordination of the various stages of the transducer transmitting ultrasonic vibrations from an ultrasonic energy generator through an energy concentrator of vibrations to percussion needle elements, for impact (with a metal product) and plasticization of a metal product in bore zone of the outer surface. Thus, the configuration of the converter is critical.

For example, a transducer structure with a plurality of steps I + II, III and IV in accordance with FIG. 4 and with equivalent steps 2, 4 and 1 in accordance with FIG. 5 all have sensitivity characteristics with intrinsic mechanical resonance. Therefore, in accordance with the present invention, the various stages of the transducer are specially designed so that they have resonant frequencies associated with the fundamental ultrasonic vibration frequency generated by the magnetostrictive transducer 28. In this regard, the eigenfrequencies of steps II, III and IV of the transducer block of FIG. 4 and the corresponding steps 2, 4 and 1 of the converter unit of FIG. 5 are individually tuned to the natural resonance frequency, which is a multiple (it is a harmonic. - Note by the translator ) fundamental ultrasonic vibration frequency. This allows you to concentrate the vibrational velocity in the shock elements and produce their vibration at a much higher speed, so that the vibration energy transmitted to the shock needles is maximum. It should be borne in mind that when the resulting operating frequency of the shock needles is a harmonic frequency that is much higher than the main ultrasonic frequency of the oscillation generator, this gives a higher speed v to the shock needle and allows the v ² component of the kinetic energy of the shock element to generate enough energy for in order to plasticize the surface of the product material to a substantial working depth below the surface of the impact and compress the body of the product with the application of an energy level that is equal to the maximum Ruggedness material or above.

Moreover, the steps of the transducer are designed with the instantaneous effective resistance of a separate stage at the moment of contact with the indenter element in the power shock cycle, which is associated with both instantaneous mechanical stresses in various stages (U) and instantaneous oscillation velocities (V) reduced to contact points of indenter elements using the U / V ratio, which is the same for each step. This ensures efficient transmission of maximum power of vibrational energy from one stage to another stage.

For the converter shown in FIG. 5, the resistances of the various stages are adjusted and can be expressed as follows: R = U1 / V1 = U2 / V2 = U3 / V3 = U4 / V4. Thus, in accordance with the present invention, it is provided that the instantaneous active resistance R is established when the shock energy transfer head is in contact with the indenter element, which is mainly equal to the instantaneous active resistance of the corresponding individual step from the plurality of steps.

Figure 5 shows the oscillation excitation system, which includes: a device (casing) 3 with an (ultrasonic) transducer and a transducer (transformer) of oscillation velocity 2, indenter elements 4 and product 1. The energy balance in such a system is determined by the equality of kinetic energy the output of the system and the potential energy accumulated in the product due to plastic deformation of its treated surface, ultrasonic deformation and relaxation of the product material in an ultrasonic wave in accordance with the above. Usually, from a functional point of view, the energy balance equation can be written as follows:

M3 (V3) ^2/2 + M4 (V4) ^2/2 + M1 (V1) ^2/2 = C1 (X1) ^2/2,

in which M (1, 3 and 4) are the corresponding equivalent masses of the product, device 3 and indenter elements, reduced to shock points on the surface of the product;

V (1, 3 and 4) represent the corresponding maximum vibrational velocities of the product, device 3 and indenter elements, reduced to shock points on the surface of the product;

C1 represents the equivalent coefficient of elasticity of the product, reduced to impact points on the surface of the product;

X1 represents the equivalent elastic deformation of the product caused by equivalent plastic deformations of the product, ultrasonic deformations and relaxation of the material of the product in an ultrasonic wave arising in the product due to ultrasonic impact.

It should be borne in mind that each indentor element of FIG. 5 excites oscillations of the new “added” mass in the product, as a result of which the equivalent mass M1 increases and, therefore, the kinetic energy at the point (s) of impact (impacts) decreases. According to the energy balance equation, an increase in the kinetic energy of impact (impacts) leads to an increase in the energy induced in the surface and material of the product, which, in turn, is equivalent to the potential energy accumulated in the product during ultrasonic collision. The results obtained by this process include: an increase in the depth of processing, an increase in the induced compressive stresses and their level in the region of maximum strength of the material, optimization of the phase and crystal structure of the material of the product and the spatial component of the regular macro- and microrelief of the treated surface.

Next, with reference to figure 5, which shows the casing 3 of the oscillating transducer, which is pressed by the spring against the working surface, and also shows the transducer block 2, indenter elements 4 and article 1, various coordinated oscillation systems that are used for application will be described appropriately calculated ultrasonic shocks to the surface of the product 1, uniformly throughout the scanning picture, due to which, in a controlled manner, they achieve an increase in surface cleanliness, hardness, compressive voltages and the shaping surface as well as corresponding removal of subsurface defects, including replacing residual tensile stresses compressive stress, and adjustment machining, etc., which is achieved by plasticizing procedures excited by impact machining.

Thus, by creating in the matrix of a multi-stage transducer a set of conjugate steps having corresponding intrinsic resonance characteristics harmonically associated with the ultrasonic frequency of the excitation energy from the specified energy excitation system, massive metal products can be plasticized in depth from the surface to provide specified technical characteristics, in in particular, the ability to correct traces of tool processing in the manufacture and correct other residual Efekt. The present invention provides improved methods of ultrasonic impact for plastic deformation of a subsurface metal and for preparing the texture of the surface zone of a product for tasks such as applying a protective coating or for creating specific patterns of texture of a surface and subsurface macrorelief and microrelief, and plastic deformation of the subsurface metal allows eliminate intergranular disorder, while plastic e deformation and compression of the subsurface metal is carried out in accordance with the surface configuration of the product to provide the selected characteristics, and plastic deformation of the subsurface metal is performed in such a way as to compress the surface layer of the product to a significant depth and maintain the residual compressive forces introduced due to processing in order to increase dimensional stability , fatigue strength, dynamic and thermodynamic service life and other introduced modifications of massive metals products of the following nature, given in specific examples.

Fig. 6 schematically shows the indenter elements 4 shown in Fig. 5, which are part of the free axial movement of the impact elements 12 ", which were discussed with reference to Fig 3. It should be borne in mind that the sets of these indenter elements, which perform random or controlled aperiodic strokes with the transfer of energy to the surface of the product 1, when the indenter elements are driven by the impact surface 36 of the transducer, can oscillate between the impact surface 36 and the surface Stu products 1 on a periodic ultrasonic frequency which is much higher than the fundamental frequency of the ultrasonic vibrations. For example, the selected individual indenter element 35, which operates in the free axial motion mode and receives kinetic energy during the impact operation by abutting against the oscillating surface 36 of the transducer, vibrates between two horizontal lines when the product is scanned using the transducer head in the processing direction 37. The indenter element 35 is shown in different positions in phase relative to the source of periodic excitation, as the Converter moves to the right in the direction processing lenii 37 along the surface of the product 1, depending on the different positions the surface of the transducer 36 and the topography of the surface 1 of the article. At point 38, the indenter element is shown in free flight after contact with the surface 1 of the product to transfer its kinetic energy to it, after its movement, caused by contact with the surface 36 of the transducer, in phase between the limits of vibration 39 and 40 for different positions or phases of vibration of the abutment surface 36 converter. Due to the emphasis in the oscillating transducer, the indenter element 35 at the vibration limit 39 receives energy transfer from a source of ultrasonic energy exciting the transducer. Therefore, the indenter element 35, depending on the boundary conditions on the surface 36, can vibrate both in a controlled and random manner, but aperiodically, despite the fact that the output (resistant) surface of the transducer vibrates only periodically. Due to this, the indenter element 35 collides with the surface of the product 1 randomly or in a controlled manner and transfers its energy to it, after which it bounces off the surface of the product 1 at moments that are determined by the relative positions of the correspondingly oscillating surface 36 of the transducer and the macro or microrelief pattern on the surface of 1 product. This characteristic allows us to propose a new regime of ultrasonic impact machining of heavy metal products, which is controllable in nature and therefore applicable to various surfaces of products and products with different masses, surface characteristics and configurations of products, and ultrasonic impact energy is supplied using individual indenter elements 35 that are in the set of matrix 4 indenter elements.

We now turn to the consideration of Fig. 7, which schematically shows the surface 1 of the product when machining by the method in accordance with the present invention, wherein the irregularities 45 represent the initial state of the surface with traces of processing the tool on the surface due to the previous processing, while the ultrasonic impact machining allows plasticize and smooth the surface 1 of the product, which has residual traces of tool processing, arising, for example, due to processing by a cutting tool and and due to the grinding. The resulting plasticized surface 1 in the process of ultrasonic impact machining in accordance with the present invention obtains a microrelief or macrorelief due to plasticization of the product metal on the surface in the selected contact zone and in the adjacent subsurface region, which leads to the formation of plastically smoothed product surfaces and compression of the subsurface layer products to a depth exceeding the specified depth of wear of the surface of the workpiece.

It is important that the product after processing in accordance with the present invention will have a hardness higher than its yield strength and mainly at its tensile strength, over the entire processed subsurface depth, which is more specifically shown in the related patent application US No. 09/653987, which describes a specific version of the brake pad system. It is also important that the product is processed at ambient temperatures, which became possible due to the instantaneous nature of the impact with the help of shock needles into a small area of the body surface of the product, with such a cyclic load schedule in which thermal energy is quickly absorbed in the product’s body, acting as a heat sink, which made it possible to produce ultrasonic treatment of the product mainly at ambient temperatures.

As shown in figa-9E, can be used various typical surface configurations of metal products, which in the process mechanically interact when performing a given working function with other surfaces and environments. These product surfaces typically experience surface resistance; contact with the environment; fatigue and wear when they are exposed to the conditions of specified working external conditions when working as equipment items, structural elements, etc .; and also experience compressive forces when they interact with the mating surface. The processing method with the creation of ultrasonic impact deformation in accordance with the present invention allows to obtain the required level of local thermomechanical influence on the structure of the material necessary to establish specific levels of wear resistance during friction, resistance to contact fracture, cyclic fracture, thermocyclic fatigue, corrosion fatigue, magnetization and unwanted deformation of the form. This is achieved by achieving a predetermined and improved hardness, reducing surface roughness, reducing residual mechanical stresses, increasing contact strength, fatigue limits, reducing friction coefficients, increasing reflectivity and corrosion resistance. Used technical operations in accordance with the present invention include heat treatment, plasticization and compression of the outer layer of the metal of the product using shock ultrasonic processing procedures that allow heat treatment, surface alloying or other changes in the texture and surface characteristics of materials, for example, the application of protective coatings with specified surface texture, as well as polishing, finishing rolling and removal of residual defects. It was found that the methods of ultrasonic impact machining in accordance with the present invention allow to obtain, by plasticizing the metal of the product in response to ultrasonic impact surface treatment and compression (metal of the product), a new surface layer and an adjacent subsurface region going to a considerable depth, which allows you to maximize the strength of the body of the product and due to this significantly increase the service life in comparison with previously known methods, such as hardening balls, which can improve the body strength of the product above the yield stress, wherein the plasticized metal.

Thus, in accordance with the present invention, improved methods for treating the working surfaces of metal products with various configurations and weights, such as those shown in FIGS. 10 and 11, using a set of ultrasonic shock elements processing the external surface areas of the product to conduct surface and subsurface are proposed. modifications, due to which structural defects are removed and the specified characteristics of the surface zone are achieved, the hardness of the working surface is increased section and the expected life of the product in the operating conditions influence the surface compressive forces from the environment or the mating piece, under static or sliding contact and interaction with other external destructive forces, including, for example, when exposed to corrosion fatigue and thermomechanical fatigue.

On figa-9E shows several examples of representative working surfaces of the collision with the mating surfaces in the compression and sliding mode in accordance with the present invention, including cylindrical surfaces such as surfaces 50 of ring bearings, fillets 51 and flats 52 for surfaces of couplings, which can be superimposed in the immediate vicinity of the configurations of cylindrical surfaces or directly on them. Flat surfaces 53 with conical chamfers that can be used in wedges, pins, and pressure bars, and flat surfaces 54, are other types of surface structures that are used, for example, as structural crossbars that receive static compressive forces such as vibration, application of load and corrosion. Work surfaces are subjected to local thermomechanical plasticization in order to modify the surface texture and create compression layers to increase surface strength due to the ultrasonic impact machining methods in accordance with the present invention. In addition, products of complex configuration, such as machine parts, guides 55, and propellers shown in FIGS. 10 and 11, which have different curvatures, masses, and angled protrusions on mating work surfaces, can be subjected to thermal plasticization and ultrasonic treatment using advanced ultrasonic transducer and impact methods in accordance with the present invention.

The propeller preform shown in FIGS. 10 and 11 is an embodiment of the product of the present invention having various surface configurations that are shown to illustrate various initial conventional processing operations carried out in the initial stages of manufacturing, and in the final stages of manufacturing, processing these surfaces are produced using ultrasonic shock methods in accordance with the present invention. This type of metal product is machined using ultrasonic impact machining of the surface, which causes surface and subsurface plasticization, creates compressive forces to control the surface and subsurface texture, and also gives strength to the product at the interface, which is higher than the yield strength of the body of the metal product and approaches the limit metal strength. The treated surfaces of the product are characterized by a distributed pattern of compression dents in the areas of contact with the impact element.

Turning now to FIG. 10, a schematic cross-sectional view of a propeller 60 is shown, which is a metal casting with blades 61 extending from the hub 62. The fillets 63, 64 that are on the back surface are shown by respective pairs of dashed lines. The main portion of the blade shown in Fig.11. The shaded area 66 is a region that is reprocessed during the manufacturing process, in which defective areas are removed by grinding before heat treatment, welding 71 and applying surface coatings 69, for example, in the previous stages of manufacture. Defective areas and weak areas are subjected in accordance with the present invention to ultrasonic local thermomechanical surface impact treatment with increased amplitude, which plasticizes and compresses the outer metal layer on the surface of the product, including adjacent subsurface areas.

Thus, the improved methodology in accordance with the present invention is used, for example, to correct defects caused by welding during repair, internal voids and cracks, thermal and corrosion deformation gradients of base metals and propeller blades due to processing configurations of the fillet and hub, as well as processing surface configurations to replace conventional manufacturing and heat treatment operations. Ultrasonic shock heat treatment in accordance with the present invention is carried out at product temperatures corresponding to ambient temperatures in order to redistribute the compressive stresses and eliminate tensile stresses arising from the correction of the above defects by welding, grinding and shaping the surfaces of the propeller, reshaping the surface texture and compressing the metal in the outer layer to a significant depth to obtain greater strength and increase service life. The stress gradients of the welded joints and the boundaries between the propeller structural components having different configurations arising from the manufacturing operations are subjected to localized thermomechanical impact machining operations to correct the propeller defects and increase the operational strength. The reliability of the propeller is improved as a result of applying the methodology of the present invention by reducing the resistance to movement in water, reducing cavitation defects and increasing fatigue resistance, maximizing the corrosion fatigue limit and leveling (distribution) of strength between the components of the propeller, such as blades and hub. In addition, surface treatments that can be carried out in accordance with the present invention improve corrosion resistance in the presence of sea water and reduce stray vibrations of the blade under conditions of hydrodynamic loading with variable amplitude. The strength of the metal of the working interface is significantly increased, which allows to withstand compressive forces to the ultimate strength of the body of the metal product. Moreover, this methodology, if introduced at the final stage of manufacturing, reduces the complexity of manufacturing and the cost of technological equipment, which leads to a significant reduction in the cost of manufacturing and repair of the propeller compared to conventional known processing methods.

Known technical solutions aimed at solving the problems of increasing the durability of the propeller, including heat treatment processes, are described, for example, in the following publications: N.N.Sokolov et al. Stainless Steel Propellers, Sudpromgiz, Leningrad 1960; Sokolov et al., Propellers in Aluminum Bronze, Sudostroenie, Leningrad, 1971; and I.I. Bogoraz et al. Propeller Manufacture Reference Book. Sudostroenie, Leningrad, 1978. Methods of strain hardening, such as hammer hardening and shot peening, applicable to the surface of blades, fillets and hubs, are described in the following publications: I.I. Bogoraz et al. Propeller Manufacture Reference Book, Sudostroenie, Leningrad, 1978; and E. V. Zvyagintsev et al. Controllable Pitch Marine Propellers, Sudostroenie, Leningrad, 1966. These methods create compressive stresses on the surface of the propeller. However, by their physical nature, they are deprived of the ability to control the processing parameters, which allows to achieve a given surface cleanliness, which is so important for the propelling surface (for the propeller surface).

In accordance with the present invention using ultrasonic shock technology in accordance with the document IIW Doc. XIII-1857-99, Lisbon, 1999, based on the improvement of the conversion (transformation) of harmonic oscillations of an ultrasonic transducer into controlled aperiodic force pulses on the treated surface. This can be achieved through the use of a low energy level not exceeding 2000 W and a high specific power of at least 300 W / cm ² , using mobile equipment, with a tool weight of 200, depending on the frequency and power of the converter, g to 2.5 kg, in the frequency range from 44 to 27 kHz. Improvements in accordance with the present invention also allow for precise settings and automatic control of processing parameters, impact force and surface quality.

Some of the main characteristics of the propellers, which are primarily determined by the state and properties of the surfaces of the blades, the hub and fillets, when working in aggressive and hard sea water, include: resistance to movement in water, cavitation strength, fatigue resistance, corrosion control, distributed the strength of the blades and the hub, the acceptable cost of manufacturing and repair, etc. The range of processed and corrected defects includes: subsurface pores, shrinkage and gas shells, intergranular cracks and hair cracks, geometric deviations from design configurations and the size of the fillets of blades, hubs, etc. Well-known conventional technologies make it possible to remove these defects by machining, arc welding, machining followed by heat treatment in a furnace at a temperature of thermal tempering of at least 600 ° C for a period of at least 6 hours. The present invention allows to correct these defects formed due to machining with subsequent welding, through the use of ultrasonic impact machining. In this case, the heat treatment operation in the furnace is excluded and energy savings of at least 10,000 kW for each propeller with a diameter of more than 3 m are achieved. Usually it is necessary to process the propellers with a span of 300 mm to 12,000 mm or more. Defects in the immediate vicinity of the fillets and sudden changes in direction can be ideally processed using lightweight movable shock transducer blocks, such as the kit shown in FIG. A mechanized scanning tool, such as that shown in Fig. 8, provides uniform ultrasonic impact processing in selected treatment zones, and this tool can be adapted by specialists for the use of automatic time-keeping and energy control systems combined with it, depending on the nature of the product, configuration and goals heat treatment, which can be successfully replaced by ultrasonic impact treatment.

We now turn to the consideration of Fig. 11, which shows a propeller in which defects were detected using ultrasonic, x-ray, fluorescence and / or other non-destructive testing and introscopy, remaining after the usual manufacturing operations, such as coating, heating, grinding machining, welding and removal or deposition of metal on the body of the propeller. In this case, portable ultrasonic shock transducers are usually used for ultrasonic local impact thermomechanical plasticization of the surface and subsurface region in the treatment zone in order to remove defects, create a given surface texture, increase strength and improve functioning, and also increase the service life of the propeller.

Conventional previously known types of heat treatment of the entire propeller body in the furnace cause different masses, configurations, and regions of the propeller boundaries to experience different residual stresses and thermal deformations, which impairs the performance of the propeller when performing its desired service functions for a long or short time lapse. The previously known operation of grinding the surfaces of the propeller not only leads to the creation of undesirable characteristics of surface roughness, but also introduces undesirable surface tensile stresses, resulting in damage to its own surface, facilitating corrosion under the influence of hydrodynamic loading of various amplitudes in the presence of sea water. This disadvantage can be corrected using the present invention by creating a plasticized surface under controlled conditions, using ultrasonic thermomechanical shocks using sets of shock elements that in a controlled manner, as well as randomly and aperiodically, strike the surface when it is scanned in accordance with a predetermined processing picture in a given processing zone.

Thus, the propeller 60 shown in FIG. 11, having a blade 61, a hub 62, and fillets (63, 64 in FIG. 10) with different masses and surface configurations, can be subjected to ultrasonic impact treatment in both surface and subsurface areas of the blade using the above transducer (tool) in accordance with the methodology of the present invention. It should be borne in mind that the propeller 60 is also a representative example of other bodies of metal products having different configurations and mass distributions and having surface zones for strong interaction with other environments, for example, is an example of bodies of metal products shown in Fig.9, which create specified levels of resistance to wear during friction, cracking, fatigue failure, corrosion, tensile stresses and surface inhomogeneities. To do this, the surface zones of these metal bodies are scanned using sets of percussion needle indenters with freedom of individual relative axial motion in a given range of motion, in response to the emphasis (impact) on the excitation surface of the ultrasonic energy transducer, which creates an increased kinetic energy required for plasticization and compression of the surface and subsurface regions of the metal body to a significant depth, which allows you to control onfiguratsiey surface, roughness, hardness, compressive stress, the contact force outside fatigue, grain structure, corrosion resistance, and allows to eliminate subsurface defects. It should be borne in mind that these needle impact elements operate in the mode described with reference to Fig.6.

Thus, the proposed methods of ultrasonic shock plasticization of the body of a metal product allow you to transfer the required energy to the surface of the metal body from the energy-generating system of ultrasonic vibrations, due to the strong impact with a high speed of the set of shock elements with the surface area of the product. The levels of transferred energy are easily controlled in order to obtain the desired results with the corresponding masses and speeds of the impact needles, with the corresponding ultrasonic frequency and amplitude of oscillations, etc. The preferred embodiment is characterized by the presence of a coordinated energy converter containing physically interconnected groups of coordinated sequentially located conjugated subsystems, as described previously here. Each of these subsystems has a characteristic of its own resonance, selected in the form of a harmonic of a given unit primary (main) ultrasonic frequency of a pulsed excitation energy source, due to which the excitation of forced intrinsic resonance oscillations using an existing ultrasonic energy source significantly increases and concentrates the available output energy, which allows directing set of percussion elements to the surface of the workpiece.

Individual indenter elements with axial freedom of movement, located in the indenter set of the transducer head, which oscillate due to the stop (collision) in the excitation surface of the energy transducer, which oscillates at the primary ultrasonic frequency, collide with the surface of the product in a controlled and random aperiodic manner, with energy, sufficient to plasticize the subsurface regions of the metal in the body of the product. This surface treatment of the product in a new way, allows you to obtain, if desired, smoother or rougher surface characteristics during the plasticization phase of the operation. Sub-surface treatment, followed by hardening of the plasticization zones of the product, allows you to apply significant compressive forces and maintain a compressed surface layer of metal to absorb forces exceeding the yield strength of the metal of the product, such as cast iron. Various elements of the product, which are connected, for example, fillets, undergo uniform processing, which reduces stress levels and leads to increased performance and service life of the product.

These characteristics and advantages of the present invention can be used, in particular, when processing the propeller 60 shown in FIG. 11, in which the “molded” main section 70 of the propeller blade 61 is filled with additional metal 71, for example, by surfacing 72. This creates unwanted internal tensile stresses close to the weld boundaries that can be mitigated by plasticization using the ultrasonic impact machining methodology in accordance with the present invention, using hydrochloric to selected surface areas of the propeller blades after welding and grinding operations carried out in a conventional manner.

As already mentioned here, the present invention eliminates the heat treatment of the propeller, usually carried out after welding to remove defects, to relax and reduce the level of residual stresses after welding, to increase the dimensional stability of the propeller during operation, to ensure geometric accuracy indicated in the drawings, and increase fatigue and corrosion resistance.

Defects in the form of gas shells 73, which appear in the restructured initial casting, can be eliminated by machining followed by welding and processing of the deposited metal, by plasticization in accordance with the methodology of ultrasonic impact machining in accordance with the present invention. Similarly, pore clusters 74, intergranular cracks and boundary defects 75, defects in the weld seam 76, and defects in joining the boundary surfaces of the casting using the added material 77 can be eliminated by plasticizing the subsurface areas by applying randomly applied ultrasonic shocks to the surface using a set of individual percussion needles making free axial movement. Thus, the residual stresses due to welding are weakened by means of a surface impact, performed with a set of free axial movement indenters, which strike in a controlled and random manner with the surface in the immediate vicinity of the welded zones, as provided for in accordance with the present invention. In addition, the surfaces of the interface between the blades, the hub and the fillet surfaces are treated in order to reduce the residual stresses of manufacture and create a surface with higher corrosion resistance, for example, by creating a compressed surface and subsurface outer layer having higher strength.

Next, the nature of the processing process in accordance with the present invention and obtained after processing the product will be described more generally. To do this, we turn to consideration of Fig. 12, which shows a graph of the dependence of strength on stress, showing the dependence of the plastic zone on temperature for a cast iron product, when it is loaded in a given operating mode, for example, during compression of a rotatable bearing when ultrasonic treatment of the base metal is performed products according to the method in accordance with the present invention. The graph shows the yield strength S of the material for various temperatures. So, for example, at 100 ° C, the yield strength of the working material is reduced to 73% of the yield strength of the material at ambient temperature (20 ° C). Thus, it is advantageous to process the metal of the article at ambient temperature in accordance with the present invention, which is discussed in more detail below with reference to FIG.

On Fig shows a classic curve of the dependence of stress on load for the product material, and the stress force F is plotted on the vertical axis, and the deformation is plotted on the horizontal axis. On the curve there are three deformation zones (I, II and III), which relate to the operation of machine processing and operation of the surface of the product, which is affected by compression and sliding forces when interacting with mating surfaces. The proposed method of ultrasonic treatment creates deformations due to compression of the metal in the surface zone, which are close to the tensile strength of the metal in zone III of the curve, while previously known methods, such as hardening, work with the plastic state of the metal of the product, that is, in zone II, below yield strength.

FIG. 14 shows two mating surfaces 78 and 79 of a metal product, with different levels of deformation being introduced into the surface of the product 78 by ultrasonic impact machining by the method in accordance with the present invention, as shown schematically. The mating surface region or region 87 of the support is loaded during a given operation of the product. The corresponding subsurface layers are shown as zones I, II, and III. It is important to note here that the working surface of the treated metal is compressed and therefore is in zone III close to the tensile strength of the base metal of the body of the product. Below this outer protective layer of compressed metal having high strength, in the deformation zone II of FIG. 13 is a layer of material deformed to its yield strength. The elastic region of the body of the product remains in zone I of Fig. 13.

Thus, as shown schematically in FIG. 14, the compression force exerted by the high kinetic energy needle indenters in accordance with the present invention creates surface strength in zone III of the maximum material strength during machining of the product, which allows for a cast iron product obtained in the plastic state II, to obtain a working surface having a more strongly compressed surface layer for interaction with the conjugated part, usually in compression mode and sliding contact KTA. This leads to a higher allowable effort and a longer product life.

To achieve this result, as shown in Fig. 15, an impact needle element with a small cross-sectional area is used, which collides with the working surface and compresses it at high speed when implementing ultrasonic impact machine processing methods in accordance with the present invention.

From the deformation characteristics shown in FIG. 13, it can be seen that the first plateau (flat portion of the curve) is formed when the impact forces reach the yield strength of the material in zone II and form plastic dents in the product material.

This differs from the region of zone III, in which the ultrasonic impact machining method introduces deformation into the surface layer of the product, leading to hardening of the compressed surface working layer of the product to a depth of 2 mm, at a point in the range from 0.9 to 0.95 of the maximum strength of cast iron, which can significantly increase the allowable working forces of compression and leads to the elimination of previously known stress concentration at this surface and to reduce the development of cracks during operation. In this case, the total depth of the layer, which includes the aforementioned hardened layer, an elastic layer of compressive stress and a layer relaxed by pulsed and ultrasonic stresses, extends to a depth of at least 12 mm, which exceeds the expected wear depth during long-term operation a product such as a bearing or brake drum. When ultrasonic shocks are applied while scanning the entire working surface of the product using impact needles, this improved method provides a uniform surface texture on the surface, ranging from light roughness with microtexture for applying the coating material, to mainly optical smoothness, desired, for example, for the preparation of the propeller blades. Previously known methods of surface hardening form regions of plastic deformation with introduced compressive stresses not exceeding the yield strength of the material, to depths of about 2 mm, and therefore cannot significantly increase the service life until complete wear of the product, compared to what can be obtained due to the combined action of ultrasonic shock and wave, with the creation of compressive stresses equal to the tensile strength of the treated material, with elastic and relaxation effects on the material to depths up to 12 mm from surfaces in accordance with the present invention.

Thus, the ultrasonic impact machining methods in accordance with the present invention increase the friction wear characteristics, the performance and the service life of the surfaces of rotary bearings, and these methods can easily be implemented using the shock elements excited by the ultrasonic transducer and machine processing systems in accordance with this invention, which allows to increase the expected service life of specific products. Ultrasonic shock energy is applied at an intensity level sufficient to create patterns of surface and subsurface deformation, which provide increased strength in the surface layer and a balanced distribution of forces in zone I of the elastic volume of the base material of the body of the product (Fig), which together with the outer textured surface, suitable for specific use of the product, reduces thermomechanical fatigue and fracture due to scuffing or seizing or thermal cracking in dry sliding contact and frictional loading of the working surface.

On Fig-23 shows the improvement of fluidity of the fluid 80 past the surface 81 after its ultrasonic impact machining. It is known that the fluid flow flowing past a smooth surface has a wetting layer 82 of medium thickness at surface 81, where the velocity is close to zero, and the flow velocity increases with distance from the contacting surface (Fig. 17). On Fig shows a graph of the relative velocity of the fluid 80 flowing past the surface 81, as a function of the distance from the contact area between the fluid 80 and the surface 81. As a result, at the contact point of the surface 81, this flow is turbulent and contains vortices 84 with cavitation properties. These vortices 84 are relatively evenly distributed depending on the properties of the fluid 80, as shown in FIG. These vortices 84 lead to the effect of swell (pulsation) in each vortex 84, with a high degree of surface cavitation. This destroys and reformed the vortex 84 at the surface 81, which leads to the formation of pockets with a high concentration of surface erosion cavitation 85 and to corrosion. These areas attack surface 81 and cause severe surface erosion and corrosion fatigue. This manifests itself on surface 81 through pitting, which ultimately leads to cracking and premature failure. The distance between the centers of two adjacent vortices, which is directly related to the size of the vortex 84, is shown in FIG. 18 as a function of the flow rate of liquid 80 past surface 81. As the flow velocity increases, the distance between the centers of two adjacent vortices 84 decreases. This leads to an increase in the concentration of surface erosion cavitation 85 on the surface 81.

The specific force of the cavitation explosion (SPCE), which is a function of the size or frequency of the vortices, determines the distance between adjacent vortices, as shown in Fig. 19. The greater the distance between the centers of the vortices, the smaller the SFCE value. The smaller the distance between the centers of the vortices, the greater the SFCE value. Thus, since the distance between the vortices depends on the flow velocity (Fig. 18), SFCE is a function of the flow velocity, as shown in Fig. 20. On Fig shows that if the flow rate increases, the activity of erosion cavitation on the surface of the stream increases. These relations and observation results are valid for smooth surfaces. This turbulent effect also affects the body's ability to move in the environment. When the body moves in a turbulent flow, then additional energy is absorbed to overcome the resistance of the medium, which is called resistance to movement. Turbulence violates the stability of movement and creates adverse and potentially dangerous resonant vibrations in a moving body. In addition, the Bernoulli effect, associated with the velocity gradient inside the combined vortices at the surface, leads to an uneven distribution of pressure in the volume of the moving body. Such pressure fluctuations cause cavitation in the fluid. With a certain ratio between the speed and pressure in the flow, cavitation, in turn, causes erosion of the flow surface, violates the hydrodynamic characteristics of the body around which the fluid flows, and eventually forms concentrations on the surface, which, in turn, give rise to dynamic and fatigue destruction. An example of such a body moving in a liquid medium is the ship’s propeller or ship’s hull.

As shown in Figs. 21-23, the surface macro- and microrelief of such a body changed as a result of ultrasonic impact machining changes the fluid flow parameters 80 at the contact boundary between the body surface 81 and the fluid 80. Ultrasonic impact machining results in superposition of macro- and microrelief on the surface 81 of the body, so that the geometry of this relief is combined with a possible combination of gaps between the centers of the vortices.

This effect is shown in FIGS. 21, 22 and 23. The new surface topography of the surface 81 formed in accordance with the present invention results in the geometry of the surface 81 corresponding to the surface of the vortex flow flowing past the surface 81. Using the graphs shown 17, 18, 19 and 20, it is possible to predict the phase shift and the size of the vortices, as well as their overlap.

In addition, the liquid 80 fills the depressions (recesses) on the surface 81 obtained by ultrasonic impact machining, and is mainly held in them. Due to this, the liquid layer in which the velocity at the surface 81 is almost zero (shown in Fig. 16) is not in direct contact with the surface 81 of the moving body, as shown in Figs. 21, 22 and 23, which leads to laminar flow 86 relative to the surface 81 and forms a protective shield for the moving body. This new situation radically reduces the velocity gradient, eliminates the prerequisites for the formation of vortices and, therefore, for the possible formation of a turbulent flow. This provides the prerequisites for the formation of laminar flow 86 relative to the surface 81.

Due to the laminar flow 86, motion instability phenomena that are unfavorable and are present during turbulence are eliminated. As a result, there are no resonant vibrations of the body during its movement in the flow and there are no energy losses due to the resistance of the medium in a state of turbulence. Consequently, cavitation and surface damage arising from turbulence are excluded, and therefore there is no danger of unpredictable dynamic and fatigue failure.

Thus, the present invention provides a new way to increase the service life, increase the reliability and durability of bodies exposed to intense flow of the medium and currents. In accordance with the present invention, a new principle of hydrodynamics and surface geometry and configuration. There is always the possibility that new vessels may fall under conditions of exposure to intense fluid flow. The present invention allows vessels to move in a liquid environment under conditions of laminar flow and not be at risk of premature destruction due to the intense effects of turbulent flow. This leads to a new method of reducing the resistance in the flow, which improves the hydrodynamics of body motion in the medium, and to a new method of protecting the surface in an aggressive environment.

In accordance with the present invention, it is proposed to process a metal product that allows plasticizing the surface of the product and adjacent subsurface areas due to ultrasonic shock using a set of shock elements performing free movement along the axis, excited by the transmission of vibrational energy from the surface of the transducer oscillating at a single ultrasonic frequency, as a result of which, in a random or controlled manner, they produce a strong blow to the working boundary surface metal products using the percussive elements in the set, which creates sufficient kinetic energy to plasticize the surface of the product and the adjacent subsurface area to a substantial depth, while the product is at ambient temperature.

The new transducer in accordance with the present invention is multi-stage and contains many series-connected stages having different conjugate difference resonant frequency characteristics harmonically associated with a single frequency of the ultrasonic energy source, and this transducer is characterized in that the set of shock elements having freedom of axial motion, which excited by an energy source with a single ultrasonic operating frequency, random manner (asynchronously) in a controlled manner or collides with the surface of the product. The scanning device moves a set of shock elements of the transducer, which come into strong contact with the surface of the product, over a predetermined processing zone on the surface of the product, in order to produce uniform heat treatment throughout the processing zone with random impacts of the shock elements, which allows plasticizing the surface of the metal product and adjacent subsurface region.

Thus, a new matrix of shock elements made with the possibility of free axial movement of the shock elements along the path of striking between the energy-exciting contact with the oscillating thrust surface of the transducer and the conversion of energy due to shock to the surface of the product, allows to obtain a new mode of driving a set of shock elements, which collide randomly with the surface of the product.

Despite the fact that the preferred embodiment of the invention has been described, it is very clear that it may be modified by experts in the field and additions that are not beyond the scope of the claims.

Claims (6)

1. A method of manufacturing a metal screw / propeller at the final stage of production, including machine-made ultrasonic percussion processing of the surface of the screw / propeller by impacting this surface with impact elements freely moving along its axis to transfer kinetic energy in an amount sufficient to convert it into potential energy, which sufficient to deform and compress surface and near-surface regions of the propeller / propeller. 2. The method according to claim 1, further comprising scanning the selected areas of the propeller / propeller with an ultrasonic transducer having a plurality of percussion elements for transmitting vibrational energy from a plurality of percussion elements to create a region of compressive stresses by plastic deformation of the surface and subsurface regions of the propeller / propeller and the formation of predetermined relief surface and structure of the material. 3. A method for changing the fluidity characteristics of a fluid relative to the body, including superpositional deposition of the microrelief and macrorelief on the surface of the body through the shock-induced impact of a set of shock elements on the body in a random or controlled aperiodic mode so that the microrelief and macrorelief correspond to the surface vortex fluid flow around the body . 4. The method according to claim 3, further comprising filling the microrelief and macrorelief with a portion of the fluid, while this fluid flows around the body in order to form a protective layer on the surface of the body and to ensure the laminarity of the fluid flow relative to the body. 5. A metal body, characterized in that its surface has many dents formed due to ultrasound-induced shock action of a set of ultrasonic shock elements on the body in a random or controlled aperiodic mode and located in accordance with possible gaps between the surface vortex flows generated at the surface of the body when fluid flows relative to the body. 6. The metal body according to claim 5, made in the form of a screw / propeller.

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