RU2113971C1 - Manual process of shot preening of cylindrical surfaces of parts with development of special device and process check and control method - Google Patents

Abstract

FIELD: shot-blasting finishing and strengthening technology of cylindrical surfaces of parts. SUBSTANCE: device which rotates turbohead by means of suspension jet flow is positioned on cylinder being worked. Rigid shot-jet ring is formed by shot-jet flow through turbohead nozzles. This ring is used for working of cylinder with false cylinders within preset travel of turbohead. EFFECT: extended capabilities of shot-preening. 3 cl, 7 dwg , 1 tbl

Description

 The invention relates to shot-hardening reinforcing technology of cylindrical surfaces of parts, namely, to finishing parts mainly of friction pairs, including cylinder blocks or engine liners, as well as compressors.

 There are devices and installations for finishing and hardening processing of parts with a cylindrical surface shape using the shot blasting method (see ed. St. USSR N 272345, N 698751, N872235, N 1553361, N 1523319, N 1609542, N 1030152, N 1569206, N 852517).

 Also known is a method of processing parts of a cylindrical shape with steel balls in a lubricating coolant (coolant), which at the same time is the tool carrier to the work surface (ed. St. USSR N 814695, BI N 11, 1981).

 The present processing process involves the impact of a single ball on a barrier that is contact-shear in nature with break-in elements, and the spot of the zone of deformation loading of the shot stream is transformed into an annular deformation loading source moving with a given feed relative to the fraction (beam) of the shot.

This type of processing improves the quality of surface treatment to (R _a = 0.16 μm) and ensures the creation of a riveted layer without the formation of a sublayer maximum of residual compressive stresses.

 Carrying out processing not on a stationary installation, but using a special compact device mounted on the cylinder of block 1, manually, standing on a car with the block head removed. And with the help of special handles and a spring, the turbo-head is lowered and raised to the length of the surface to be machined. In order to prevent metal removal at the ends of the cylinders, special gaskets 11 (called false cylinders) are installed on top of the device and below the cylinder. A flexible conduit 9 is connected to the pallet 10, which goes through the pump to the turbo nozzle of the device.

 The technical result of the invention is the expansion of technological capabilities by shot-setting the processing of cylinders in non-stationary conditions when hardening the surfaces of the cylinders to ensure uniform processing, including the boundary sections of their ends when creating a given microrelief on the treated surface.

 The specified result is achieved by the fact that in the proposed process of finishing and hardening the processing of cylindrical surfaces of parts with a fraction supplied by a liquid or gaseous stream pumped by a special pump, the cylinder is machined within the specified stroke of the turbo head along its axial feed down and up using special handles 6.

 In FIG. 1 schematically shows the proposed device, General view (the first version of the device for processing one cylinder or liner); in FIG. 4 is a general view for processing several cylinders or a pre-assembled cartridge case, in which the lowering and raising of the turbo-head must be carried out using a mechanical drive, by means of a manual, hydraulic, pneumatic or electric propulsion device.

 The device shown in Fig. 1 contains a housing consisting of a base in the form of a base support 2 and a frame 3, into which a hydraulic actuator 12 is mounted, made of a metal pipe, which has a turbo nozzle 4, through which a fluid pump 8 is supplied or an air-gas suspension, which, passing through the turbo-head 5, rotates the turbo nozzle with the turbo-head. Axial downward and upward movement of the turbohead for processing the cylinder over the entire length is carried out using special handles 6, which move along special grooves in the device frame, and return to the upper position using the spring 7. For convenience in operation, the turbo pipelines connecting the pallet to the pump and the pump with the working body of the device, set of flexible hoses 9.

 Example. The processing process of the cylinder block of a VAZ car.

Without removing the engine from the car, it is disassembled. Removed the head of the block, pan, crankshaft, pistons. Cylinders are mounted on and under the cylinders. From above, on the block above one of the cylinders, the developed device for finishing and hardening processing of the cylinder is installed. From below, a pallet is installed in its place, to which instead of a drain plug, a flexible hose connected from the pump is attached. The pressure of the supplied suspension with bearing balls is set based on the specified processing conditions, in particular, P _W = 3.0 - 5.0 MPa.

The initial surface roughness of the cylinders is 0.35 μm. The initial hardness HB 80 - 100. The installed false cylinders are identical in size to the diameter of the holes in the block, and from the same material. Bearing balls применяются 1.8-2.0 mm GOST 37622-70, III-IV degree of accuracy are used as a fraction. As a coolant - transformer oil with a surfactant additive. The frequency of the double strokes of the turbohead 5 in the vertical reciprocating direction is 3 times in one minute. At a pressure of P = 10 MPa, the turbo-head rotational speed is 800 - 1000 rpm. The obtained comparative data on the traditional operation of honing and finishing hardening with a disk-shaped shot-grinding tool formed by a turbo nozzle 4 and a turbo-head 5 show that the topographic macro- and microrelief has a better quality than after smoothing. Moreover, the roughness of the proposed method in terms of altitude parameters is R _a = 0.18 μm, as in pure diamond honing, but with a better curve of the supporting surface of the protrusions, which significantly increases the anti-wear characteristics of the treated surface. In addition, when measuring residual stresses with false cylinders, a smooth distribution with a maximum near the surface is shown, which also further contributes to an increase in anti-wear characteristics. The microhardness of the surface layer increases to 530 MPa. Comparative bench tests of cylinders after honing and additional GDO showed the exception of cases of nadroobrazovaniya. In turn, shot blasting provides the ability to constantly maintain the presence of lubricant on the friction surfaces of a friction pair, which eliminates the sticking of pistons and ruts to the cylinder walls during prolonged non-working condition of the engine in climatic conditions with long wet times a year and in air with large admixtures of chemical additives gas contamination.

 A stream of suspension with a size of glass balls of 250 - 315 μm and an energy of 2800 - 3000 J is sent to the treated surface 1 with details, at the same time, antifriction powder 3 is introduced in an amount of 10-30% of the fraction of the fraction. Balls of fraction 2, having a velocity of the order of 150-160 m / s and a maximum supply of kinetic energy, hit the surface 1, perform the work of micro-cutting and form the largest micro-cavities 4, which subsequently serve to place and hold the lubricant. Particles of antifriction powder 3, striking the surface, simultaneously create a thin coating layer 5 on it.

 In FIG. 2 shows a schematic diagram of a method; in FIG. 5 is a graph of the dependence of the depth of microcavities on the size of abrasive grains; in FIG. 3 is a view A of FIG. 4.

 The method is as follows. Using a turbo-head of a device for processing cylinders, a jet consisting of a suspension of compressed air with an energy of 2800-3000 J. is sent to the workpiece 1 to be treated. The suspension consists of grains of fraction 2 with a glass ball size of 250 - 315 microns, antifriction powder 3 in an amount of 10-30 % by weight of the content of the fraction. Balls 2, having a velocity of the order of 150-160 m / s and a maximum supply of kinetic energy, hitting the surface 1, perform the work of micro-cutting and form the largest micro-cavities 4, which subsequently serve to place and hold the lubricant. Particles of antifriction powder 3, striking the surface 1, simultaneously create thin coating layers 5, 6 with enhanced operational properties on it. Layer 5 of antifriction coating, driven into the surface with glass balls with the application of microglass coating 6 separated particles from the surfaces of the glass balls.

 Glass balls up to 50 microns in size, equal in composition to the green silicon oxide grade 63C abrasive. The samples were processed from cylinder blocks installed from the nozzle at a distance of up to 80 mm.

 The processing results are shown in the table. The dependence of the depth of microcavities on the size of abrasive grains is confirmed by the graph (figure 5), built on the basis of the table.

 As can be seen from the data in the table and graph, the maximum depth of microcavities, which characterizes the increased oil absorption, and consequently, the improved operational properties of the treated surface of the part, obtained when using a jet with an energy of 2800 - 3000 J, fractions with a ball size of 250 - 315 μm and anti-friction powder in the amount of 10 - 30% of the mass of the content of the fraction.

 Example. As an antifriction material - a mixture of powders from antifriction bronze Br А11Ж6Н6 and molybdenum disulfide DM-1, only 10% of the mass from the content of the fraction. The surface treatment of the samples was carried out instead of honing after fine boring. Glass balls (fraction), equivalent in properties to electrocorundum of normal grade. The energy of the delivered jet is 3000 J.

 Measurements showed that the greatest depth of the obtained microcavities is 14–16 μm. Compared with the honed, the specific oil absorption of the surface treated by the proposed method increased up to 5 times, the antifriction coating layer was 2-3 microns. The microhardness of the surface layer increases at minimum values from 80-120 to 250-280 units, at a minimum. Wear resistance increased by at least 2 times. Nadir formation during friction pair operation is virtually eliminated. The negative side is the additional oil consumption during running-in of the friction pair — the ring, the surface of the cylinder, which can be adjusted depending on the processing conditions, the suspensions and additives used, and also the diameter of the fraction.

 Using the proposed process using the developed device allows to expand the technological capabilities of shot blasting as a result of processing the internal surfaces of the cylinders, including the boundary sections of their ends.

 There is a method of monitoring and controlling the process of abrasive blasting of surfaces of parts (see ed. St. USSR N 852517) and can be used for shot blasting of parts with glass or steel balls when introducing additional factors used in the processing of parts into the formula.

 According to the known method, the regulation of operating speeds is carried out by assigning the operating flight speed of the tool (fraction) without taking into account the initial technological parameters, the suspension used and the antifriction powders used, which affect the critical flight speeds of the fraction, which does not allow to evaluate the processing result and thereby reduces the effectiveness of control the process of bead-blasting surface treatment of parts.

 The technical result of the invention in terms of the method is to increase the efficiency of monitoring and control of the abrasive blasting process.

где
h_о - глубина отпечатка, которую определяют при контрольных испытаниях;
d_o - приведенный диаметр частицы абразива при контрольных испытаниях;
γ₀ - удельный вес дроби при контрольных испытаниях;
V_o - скорость удара частицы дроби при контрольных испытаниях;
HB_o - твердость материала обрабатываемой поверхности при контрольных испытаниях;
S - плотность суспензии при контрольных испытаниях (без присадок и дроби);
h_п - глубина отпечатка от антифрикционной частицы, которую определяют при контрольных испытаниях;
d_п - приведенный диаметр частицы из антифрикционного порошка (присадки) при контрольных испытаниях;
γ_n - удельный вес частицы из антифрикционного порошка при контрольных испытаниях;
h₁;d₁;γ₁,v₁;h_n;d_n;d_n;γ_n;v_n;s и HB - соответствующие параметры действительного технологического процесса.The above is achieved by the fact that in the proposed method, the operating speeds are selected as the control parameter and the control is carried out by comparing the working and critical speeds depending on the cleanliness of the surface to be treated, and the control is carried out by controlling the working speeds of the abrasive, for this, the process parameters are determined taking into account the coefficients used and used powders of antifriction additives in accordance with all the parameters of the components of the condition:

Where
h _about - the depth of the print, which is determined during the control tests;
d _o - the reduced particle diameter of the abrasive during the control tests;
γ ₀ is the specific gravity of the fraction during the control tests;
V _o is the impact velocity of the particle in the control tests;
HB _o - the hardness of the material of the treated surface during the control tests;
S is the density of the suspension during the control tests (without additives and fractions);
h _p - the depth of the imprint from the antifriction particles, which is determined during the control tests;
d _p - the reduced particle diameter of the antifriction powder (additive) during the control tests;
γ _n is the specific gravity of the particle from the antifriction powder during the control tests;
h ₁ ; d ₁ ; γ ₁ , v ₁ ; h _n ; d _n ; d _n ; γ _n ; v _n ; s and HB are the corresponding parameters of the actual technological process.

 The method of monitoring and controlling the process of bead-blasting treatment of the surface of the parts by adjusting the working speeds consists in choosing operating speeds as a control parameter and monitoring by comparing working and critical speeds depending on the cleanliness of the surface being processed, and controlling by controlling the working speeds of the shot, for this is determined by the technological parameters of the process in accordance with the fractional composition from the conditions of the proposed dependence.

 In this case, the critical velocity for the shot and powder particles is determined by the destruction of the shot, by hitting the obstacle in the form of a solid smooth reference surface and a wedge-type tip. By comparing the obtained speeds, one obtains a step or a range of probable values of critical speeds during processing under actual conditions.

Critical speeds are determined for various sizes of shots and particles of filler powders, (carbide material), for example, shots of 0.5; 1.0; 1.5; and - 2 mm, powder 0.005; 0.010; 0.015; 0.02; 0,025 mm, that is, the specified multiplicity of sizes to increase acceleration and increase the strength of the definitions. In all cases, the angle of attack is maintained equal to 90 ^o and provide a constant hardness of the processed reference surface. By comparing the obtained values of the critical velocities, their dependence on the size of the fraction and particles of the additive powder is obtained.

 To ensure process control process other control or reference samples, for example, of different hardness.

During the control tests of the samples, the operating flight or impact speeds are less than critical, and under these conditions, after measuring the depth of the indent, by comparing them, the dependence of the indent depth on the impact velocity, the surface hardness of the control samples, the specific gravity and size of the shot and filler particles is determined, for example, in the form of a reduced diameter . In all cases, the processing of control samples, the angle of attack withstand 90 ^o .

 The actual processing process is controlled by controlling the operating speeds of the shot and filler particles, for this purpose the technological parameters of the process are determined in accordance with the fractional composition from the conditions of the proposed dependence and thereby control and control the actual processing process, ensuring the necessary quality and surface finish of the parts.

 In this case, the fractional composition of the working fraction and filler particles is determined by sieving through a set of sieves with a certain mesh size or separation.

 In all cases of the actual process of processing the surface of products, the working speed of the flight of the fraction and particles (or its impact) provides less critical in accordance with a clean surface than the durability of the fraction and the control and controllability of the process are maintained.

 Example. Shot blasting of samples or parts with cast iron. Pre-provide the sieving of the fraction in fractions of 0.5; 1.0; 1.5; 2.0; 2.5; mm and filler particles of 0.005; 0.010; 0.02; 0,025 mm through a separator with a set of sieves or in accordance with GOST.

 For a fraction of a fraction of one fraction or a constant size of the fraction, the destruction is provided by the action on the reference surface, and thereby the fracture energy is determined for the fraction and particles of the additive powder.

 In this case, for example, the destruction speed or critical speed are measured by a known photoelectric or other method, and the dependence of the destruction speed (critical speed) is determined for different sizes or indicated fractions of a fraction by comparing the measured speeds when processing various types of surface cleanliness, for example, smooth or wedge type ) on the size of the fraction. Small particles of anti-friction additives can also be figuratively taken as a fraction.

 Then, the other part of the fraction acts on the reference surface, while ensuring non-destruction of the fraction. Using telescopes and line measures (a microscope or other measuring instrument), the depths and widths of the prints are measured, the hardness of the reference surface is determined, and the specific gravity of the fraction is determined.

 By comparing the obtained and measured data, the dependence of the imprint depth and width on the impact velocity of the shot, its size, specific gravity and hardness of the reference surface is obtained.

 In all cases, the reduced diameter is taken as the size of the fraction, which ensures the comparability of the data obtained. For example, for a ball of this magnitude, the diameter of the ball will be.

 The data obtained are presented in tabular and then in graphical or analytical form.

 In FIG. Figure 6 shows a graph where the critical velocities (in m / s) are plotted along the ordinate axis, and the reduced diameter or size of fraction balls (in mm) along the abscissa axis; curve 1 corresponds to a round fraction, and curve 3 corresponds to optimal operating speeds.

 A comparison of these data shows that the critical speed depends on the size of the abrasive and increases with its decrease.

In FIG. Figure 7 shows a graph where the imprint depth and impact velocity along the ordinate axis and the reduced diameter (balls) of the fraction along the abscissa axis show the change in imprint depth depending on the size (balls) of the fraction with a specific gravity of 7.8 g / cm ³ .

 Tabular and graphical data show that the critical speed depends on the type and size of the shot, and the optimal working speed (equal to 0.5 critical from the condition of durability) sharply decreases with increasing size of the abrasive, which indicates the need to ensure uniform and equal (or close) the size of the fractional composition of the working fraction.

 Based on the obtained comparison data, further monitoring and control of the actual process of bead-blasting treatment of the surface of the parts is carried out by adjusting the working speeds from the condition of the assumed dependence in magnitude not higher than the optimum, equal to 0.5 critical speed, providing a given surface cleanliness in accordance with the measured hardness HB, specific gravity of the abrasive and available fraction size.

 The application of the method allows more accurately determine the operating speed, and to set and control the necessary working parameters of the technological process for each specific case and thereby increase the efficiency of monitoring and control of the process of shot blasting of products.

Claims (3)

 The method of finishing and hardening processing of cylindrical surfaces, in which the inner surface of the cylinder through the feed unit is affected by a hydroflow of a suspension including balls with relative reciprocating and rotational movement of the feed unit and the processed cylinder, characterized in that they take a false cylinder, set it on the end face of the processed cylinder , additives are additionally introduced into the suspension, and a turbohead with a turbo nozzle is taken as a node for supplying a hydroflow to the suspension, and I inform the latter t rotational movement by means of a slurry flow, which is fed through a turbo-head, while the processing process is carried out for 3-5 minutes, and the reciprocating movement of the turbo nozzle is carried out manually.  2. The method according to p. 1, characterized in that antifriction material is introduced into the suspension as an additive.  3. The method according to claim 1, characterized in that carbide material is introduced into the suspension as an additive.

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