RU2287423C1 - Method of vibration static-pulse working - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: method comprises applying static and periodic pulse loading to the deforming tool perpendicular to the surface to be worked by means of striker and feeding the deforming tool in the axial direction. The striker and wave guide are made of rods of the same diameter. The deforming tool is mounted with a spaced relation at the free end of the wave guide by means of flat springs mounted at an acute angle to the longitudinal axis of the wave guide. The springs vibrate the deforming tool in the axial direction. The amplitude of vibration varies by means of varying the space between the free end of the wave guide and deforming tool caused by varying the static loading.

EFFECT: expanded functional capabilities.

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Description

The invention relates to mechanical engineering technology, in particular to methods for finishing and hardening processing of parts from steels and alloys by surface plastic deformation with static-pulse loading of a vibrating tool.

A known method of finishing and hardening of parts by rolling [1], in which the feed motion and the processing speed of the tool and the workpiece are contacted under normal static load applied to the surface normally applied to the work surface in the range of forces ensuring the achievement of a given roughness and periodic impulse load, varying in the established range from minimum to maximum value. In this case, the load ripple frequency is selected depending on the required hardening depth.

The method is characterized by low efficiency, high energy intensity, not sufficiently large depth of the hardened layer and not sufficiently high degree of hardening of the treated surface.

A known method of static-pulse treatment by surface plastic deformation, carried out by a tool, to which a constant static load and a perpendicular pulse load, which is communicated by means of a striker and a waveguide, are normally applied to the surface to be treated, and the shape, amplitude, effective duration and frequency of single pulses of the deformation force are determined by the given formulas [2].

The known method is characterized by limited control capabilities in creating heterogeneous hardened layers and regular microrelief of the treated surface.

The objective of the invention is to expand the technological capabilities of static-pulse treatment by surface plastic deformation by controlling the depth of the hardened layer and the surface microrelief by using an oscillating tool.

The problem is solved using the proposed method of surface plastic deformation, including applying to the deforming tool normally to the work surface a static and periodic impulse load by means of a striker and a waveguide made in the form of rods of the same diameter, and the axial feed of the deforming tool, and the deforming tool is installed with a gap at the free end of the waveguide with the help of located at an acute angle to the longitudinal axis dnego flat springs providing vibrodvizhenie with an amplitude in the direction of axial feed of the deforming tool, wherein the amplitude of said regulation is performed by changing the size of the gap between the free end of the waveguide and the deforming tool by changing the static load.

The essence of the method is illustrated by drawings.

Figure 1 presents the processing scheme for the proposed method of vibrational surface plastic deformation on the example of a workpiece - a shaft installed in the chuck and the rear center of the lathe; figure 2 - the position of the tool under the action of only static load; figure 3 - position of the tool under the action of static and periodic pulsed loads; figure 4 - combined tool position: position 1 - under the action of only static load; position 2 - under the action of static and periodic pulsed loads; figure 5 is a section along BB in figure 2; figure 6 is a section along bb in figure 2; Fig.7 is a view along D in Fig.2; Fig.8 is a view along D in Fig.3.

The proposed method serves for vibrational surface plastic deformation using a constant static and periodic pulsed load on the tool, which oscillates in the axial direction.

The blank 1, for example, the shaft is installed in the chuck 2 and is pressed by the center 3 of the tailstock of the lathe, and the deforming device 4, equipped with mechanisms of static and pulsed loading of the tool, in the tool post of the machine 5 (figure 1). A hydraulic pulse generator (not shown) is used as a mechanism of static and pulsed loading of the tool [3, 4].

At the free end of the waveguide 6 with a certain clearance Z _max, a deforming tool 7 is installed using flat springs 8 located at an acute angle α to the longitudinal axis of the waveguide 6 so that under the action of a periodic impulse load P _{, the} tool 7 is shifted in the direction of the axial feed S _pr the magnitude of the amplitude A _and .

Tool 7 and the workpiece 1 reports feed motion S _ave and V _of the processing speed, enter them into contact. In the direction of the normal to the surface being machined, a constant static P _st loading force is applied to the deforming tool, which is created due to the deflection of the flat springs 8, while the gap Z _max decreases to the value Z _st .

Static loading P _{st is} carried out by means of springs 8 mounted on the waveguide 6. The value of the static deformation force is selected as the largest of those providing elastic contact deformations of the processed material.

Impulse loading P _{it is} carried out by impact of the hammer 9 of the hydraulic pulse generator (not shown) on the end of the waveguide 6, on which the tool 7 is mounted. The impact energy of the hammer 9 is greater than the stiffness of the springs 8, so the tool 7 is displaced in the axial direction (according to figure 3 - to the right ) relative to the waveguide and the gap Z becomes zero Z = 0. After the termination of the impact energy of the impact on the tool, it moves in the axial direction and returns under the action of the springs to their original position (to the left, relative to the waveguide, see figure 2).

Thus, in one hit of the striker 9 on the waveguide 6, the tool 7 will make one vibrational movement in the direction of the axial feed (see Fig. 1) with amplitude A _and , depending on the size of the gap Z and the angle α of the inclination of the springs 8.

Due to this design of mounting the tool 7 on the waveguide 6, a trace (see figure 1) in the form of a sine wave remains on the surface to be treated.

The oscillation frequency of the tool depends on the frequency of the shock of the hammer of the hydraulic pulse generator. The amplitude A _{and the} oscillations of the instrument can be controlled by changing the gap Z between the waveguide and the instrument by decreasing or increasing the static load P _{st of the} instrument, acting in the transverse direction by the deforming device 4 on the waveguide, causing spring 8 to deflect (see Fig. 2).

As a result of the impact of the striker 9 at the end of the waveguide 6, shock and oppositely directed pulses of the same amplitude and duration arise in the striker and the waveguide, each of which will affect the surface to be treated with a cycle equal to twice the duration of the pulses. Having reached the surface to be treated, the shock pulse is distributed on the passing and reflecting. The passing pulse forms the dynamic component of the strain force.

When the tool is subjected only to a static load P _st (Fig. 2), its introduction into the work surface takes place at a lower value of h _st and the tool track on the work surface has a minimum diameter d _st (Fig. 7), with a pulsed load P _them (Fig. 3) the introduction of the tool into the work surface occurs at a large value of h _them and the tool track on the work surface has a drop-shaped shape with a maximum diameter d _them (Fig. 8).

The depth of the hardened layer processed by the proposed method reaches 1.5 ... 2.5 mm, which is significantly (3 ... 4 times) more than with traditional static hardening. The greatest degree of hardening is 15 ... 30%. As a result of static-pulse processing according to the proposed method with a vibration tool, compared with traditional rolling, the effective depth of the layer hardened by 20% or more increases by 2 ... 3 times, and the depth of the layer hardened by 10% or more, by 1 , 7 ... 2.2 times.

Example. To assess the quality parameters of the surface layer hardened by the proposed method, experimental studies of the shaft processing on a lathe using a special bench were carried out. The values of technological factors (impact frequency, amplitude value, feed value) were selected in such a way as to ensure the multiplicity of impact on the elementary area of the treated surface in the range of 6 ... 10. A further increase in the multiplicity of the deforming effect leads to softening.

The value of the force of static preloading of the tool to the work surface was P _article ≥25 ... 40 kN; P _them = 255 ... 400 kN. Billets made of steel 40X; initial hardness of “raw” samples is HV 270 ... 280. The depth of the layer hardened by static-pulsed processing is 3 ... 4 times higher than with traditional rolling. The hardened layer in the traditional static rolling is formed under long-term action of large static forces. The proposed method, a similar depth of the hardened layer is achieved as a result of a short-term impact on the deformation zone of a prolonged energy pulse. At close degrees of hardening of the surface layer, the magnitude of the static component of the load by the proposed method is much less.

Studies of the stress state of the hardened surface layer by static-pulse treatment showed that the maximum residual stresses are close to the surface, as when chasing, which is favorable for most of the interfaced parts of mechanisms and machines. A comparison of the depth of the stressed and hardened layer, the stress gradient and the hardening gradient shows that the depth of the stressed layer is 1.1 ... 1.3 times greater than the depth of the riveted layer, which is consistent with the theory of surface - plastic deformation.

The ultimate roughness value achieved during processing by the proposed method is R _a = 0.08 μm, a reduction of the initial roughness by a factor of 6 is possible.

Microvibrations in the process favorably affect the working conditions of the instrument. The imposition of a small amplitude oscillatory motion leads to a more uniform distribution of the load on the tool, causes additional cyclic movements of the contact surfaces of the tool and the workpiece, facilitates the formation of a hardened surface. Fluctuations contribute to a better penetration of the cutting fluid (coolant) into the treatment area. When vibration is applied, the deforming surface of the tool periodically “rests”, which helps to increase its resistance. Processing under vibration conditions dramatically increases the efficiency of the cooling, dispersing and plasticizing action of the coolant due to the facilitation of its access to the contact zone between the tool and the workpiece.

The proposed method extends the technological capabilities of static-pulse treatment by surface plastic deformation, allows you to control the depth of the hardened layer and the surface microrelief.

Information sources

1. A.S. USSR, 456719, MKI V 24 V 39/00. The method of finishing and hardening of parts by rolling. 1974.

2. RF patent 2098259, MKI ⁶ V 24 V 39/00. Lazutkin A.G., Kirichek A.V., Soloviev D.L. Method of static-pulse treatment by surface plastic deformation. No. 96110476/02, 05.23.96; 12/10/97. Bull. Number 34.

3. Kirichek A.V., Lazutkin A.G., Soloviev D.L. Static-pulse processing and equipment for its implementation // STIN, 1999, No. 6. - S.20-24.

4. RF patent 2090342. Lazutkin A.G., Kirichek A.V., Soloviev D.L. Water hammer device for processing parts by surface plastic deformation. 1997. Bull. Number 34.

Claims (1)

The method of surface plastic deformation, including applying to the deforming tool normally to the machined surface a static and periodic impulse load by means of a striker and a waveguide made in the form of rods of the same diameter, and performing axial feed of the deforming tool, characterized in that the deforming tool is installed with a gap at the free end waveguide using flat springs located at an acute angle to the longitudinal axis of the latter, providing odvizhenie with an amplitude in the direction of axial feed of the deforming tool, wherein the amplitude of said regulation is performed by changing the size of the gap between the free end of the waveguide and the deforming tool by changing the static load.

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