RU2341364C2 - Method of vibroimpact processing of part - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention may be used for finishing and strengthening processing of bulky spatial parts of complex shape, for instance, fittings, brackets, etc., which includes part fastening in container with source environment, bringing of container into oscillating motion and its periodical realignment by means of turn, which differs by the fact that container turn is carried out in the plane that is perpendicular to the plane of oscillations, with angular pitch γ_i, value of which is selected as not more than value of angle γ of impact stripping of source environment particles from the surface of part and is determined according to the following formula: γ=arctg3.5·f, where f-coefficient of impact friction.

EFFECT: higher efficiency of method.

2 cl, 3 dwg, 1 ex, 1 tbl

Description

The invention relates to mechanical engineering, namely to vibroimpact processing, and can be used for finishing and hardening processing of large spatial details of complex shape, in which vertically and horizontally oriented surfaces are proportional, for example, fittings, brackets, etc.

There is a method of vibro-shock processing of a part placed inside a container with an abrasive tool environment, in which the latter is informed of oscillatory movements, and during the processing periodically turn 180 ° around the horizontal axis, while during the entire processing cycle the part can be processed with one or and with repeated periodic rotation of the container (description of the invention to SU 975350, MKI3 V24V 31/06, 1982).

The disadvantage of this method is the impossibility of high-quality and efficient processing of large parts. In addition, a 180 ° flip of the container does not increase the efficiency of the dynamic impact of particles of an abrasive tool environment on the machined surfaces of the part located in the plane of oscillation. This does not allow, for example, to carry out uniform processing of parts with vertical sections of the surface lying in the plane of oscillation. Thus, the technological capabilities of the method are limited.

A known method of vibroimpact processing of planar large-sized parts, carried out in a container with a fixed part and a granular working medium, in which the container is brought into vibrational motion, having previously provided its rotation in the plane of vibration by the angle of repose of the vibrational movement of the upper layer of the working medium with a fixed position. In this case, the container is rotated in the opposite direction to the vibration exciters, which is periodically reversed during the processing cycle (description of the invention to SU 1174235, MKI4 V24V 31/06, 08/23/08).

The known method provides a process with the equality of the columns of the working environment over the workpiece. This improves the uniformity and quality of processing only planar parts.

The objective of the invention is the expansion of technological capabilities, improving the efficiency and quality of vibroimpact processing of large-sized spatial parts on vibroinstallations with a flat oscillation path.

The technical result is to increase the uniformity of the processing of the part on all surfaces by creating the optimal contact force interaction of the particles of the instrumental working medium with the surface of the sections oriented during processing in the vibration plane.

The technical result is achieved by the fact that in the method of vibroimpact processing of a part, carried out in a closed container with a fixed part and an instrumental medium, in which the container is brought into vibrational motion and periodically reinstalled by turning, the container is rotated in a plane perpendicular to the plane of oscillation, not in steps of an angle more than the angle of impact disruption of the particles of the instrumental medium from the surface of the part γ, determined from the condition

(1)

(one)

where f is the coefficient of shock friction.

The container can be used with a closed internal cavity made in the form similar to the shape of the workpiece with a similarity coefficient k selected from the condition

(2)

(2)

where Δ is a value equal to 30-40 the maximum particle size of the instrumental medium, mm;

h is the height of the cross section of the part, mm

The essence of the method lies in the fact that during periodic reinstallation of the container with the fixed part by turning in a plane perpendicular to the direction of oscillation, the part is processed in an additional coordinate and at each step the angle of attack of the particles of the circulating flow of the instrumental medium with respect to the vertical sections of the machined surfaces changes. Thus, a two-axis vibration machine implements a processing scheme similar to the 3-axis oscillation scheme, which allows comprehensive uniform processing. The choice of the angle of rotation of the container with a step of no more than the angle of impact disruption of the particles of the instrumental medium from the surface of the part provides maximum contact force interaction, thereby increasing the intensity and efficiency of processing. When the container is rotated through an angle whose value is more than the selected value (1), disruption of particles is observed with slippage relative to the surface being treated.

The execution of the inner surface of the container in a shape similar to the shape of the workpiece provides the latter with comprehensive uniform dynamic contact with the tool environment in hard-to-reach areas, for example, at places where vertical to horizontal sections of the surface pass, etc. The similarity coefficient of the shape of the inner surface of the container to the shape of the outer surface of the workpiece selected from condition (2) provides the optimal ratio between the intensity of the dynamic impact of the particles of the tool environment and the useful dimensions and weight of the container with the tool environment.

Figure 1 shows a container with a workpiece, a cross section in the plane of oscillation; figure 2 shows a diagram of the reinstallation of the container with the detail in the implementation of the method; figure 3 is a section aa in figure 1.

The workpiece 1 by means of clamping devices (not shown) is fixed in the container 2, the inner cavity of which is made in a shape similar to the shape of the workpiece with a similarity coefficient selected from condition (2). A container is installed on a horizontal platform 3 in the XOZ plane of a two-coordinate vibrating machine (not shown) with the possibility of reinstallation.

To carry out vibration processing after fixing the part in the container and loading it with the instrumental working medium 4, the latter is given oscillatory motion in the vertical XOY plane and the part is processed.

After the processing period t _i, the reinstallation process with the selected rotation step γ _{i is} repeated until the completion of the vibration hardening cycle. The value of the period (duration) of processing t _i calculated according to

(3)

(3)

where t _H is the processing cycle time until the required technological parameters are achieved (roughness, residual stresses); γ _i is the rotation angle selected from the condition γ _i <γ, in which γ is the angle of impact disruption of the particles of the instrumental medium from the surface of the part, determined by dependence (1); 0 <K _N ≤2 - shape factor of the workpiece; π = 180 °.

The rotation is carried out in and / or counterclockwise relative to, for example, a vertical axis passing through the center of gravity of the container. For each type of part, depending on the complexity of the design, the direction of rotation and the number of reinstallations are chosen experimentally, including using mathematical modeling.

An example of machining a fitting part from steel 30KhGSNA.

Steel balls with a diameter of 5 mm made of ShKh15 steel and machine oil were used as the instrumental medium. For the materials used by a known method (Kobrinsky A.E., Kobrinsky A.A. Two-dimensional vibration-shock systems. - M .: Nauka, 1981), the coefficient of shock friction was determined - f = 0.127. To conduct the processing, the step of the angle of rotation γ _i of the container with the fixed part during reinstallation was chosen equal to the value γ = 0.42 rad = 24 °, calculated according to formula (1) and corresponding to the value of the angle of impact breakdown of the balls from the surface of the part.

For vibroshock processing, a container was used with an inner surface similar to the outer surface of the part with a similarity coefficient k = 1.5 calculated from condition (2). As the overall dimension of the part, its height h = 300 mm was chosen, and the value A was taken to be equal to 30 diameters of the balls of the instrumental medium. Then k = 1 + (5 · 30): 300) = 1.5.

During processing, the container in the vertical XOY plane was informed of vibrations with an amplitude of 5 mm and a frequency of 21 Hz, while the container with the part was periodically reinstalled on the platform by rotating it in the horizontal XOZ plane in increments of 24 °. The number of reinstallations during the treatment cycle t _H = 60 min until the required technological parameters of roughness and residual stresses are reached was determined from the condition that the container made a 360 ° full turn part. The duration of the processing time in each of the newly fixed positions of the container with the part (with the shape factor of the part K _N = 2) t _i = 60 min · 24 ° / 2 · 180 ° = (1440/360) min = 4 min. The processing results are presented in the table.

Table Technological parameters Process Values In the initial state After vibroshock processing without turning the container with rotation of the container in the horizontal plane hou xoz yoz hou xoz yoz hou xoz yoz roughness, Rz, microns 10-12 10-12 10-12 8-10 4-5 5-6 4-5 4-5 4-5 residual stresses, σ ₀ , MPa 0 0 0 50-70 250-320 230-310 250-320 250-320 250-320

Note: hou, xoz, yoz denote the orientation of the part surfaces relative to the coordinate planes XOY, XOZ, YOZ.

Claims (2)

1. The method of vibroimpact processing, including fixing the part to the container with the instrumental medium, bringing the container into vibrational movement and periodically reinstalling it by rotation, characterized in that the container is rotated in a plane perpendicular to the vibration plane with an angular pitch γ _i , the value of which is not chosen more than the angle γ of shock disruption of the particles of the instrumental medium from the surface of the part, determined by the formula:

where f is the coefficient of shock friction. 2. The method according to claim 1, characterized in that they use a container with a closed internal cavity, the shape of which is similar to the shape of the workpiece, while the similarity coefficient k is determined by the formula:

where Δ is a value equal to 30-40 the maximum particle size of the instrumental medium, mm; h - overall cross-sectional dimension of the part, mm.

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