RU2433902C2 - Method of static pulse strengthening - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to metal plastic working, in particular, to methods for treatment with pulse-impact surface plastic deformation. Rotation movements are given to a stock and a multi-element deforming tool around their axes. Line feed of the multi-element deforming tool is provided. A multi-element deforming tool is used, which comprises deforming elements made in the form of turns of a helical cylindrical spring, which is twisted in a helical manner and covers the stock, and a body in the form of a stator of a three-phase asynchronous shorted electric motor. Inside the body there is a rotor mounted as a hollow shaft in rolling bearings. Deforming elements are installed in the rotor hole on an elastic bushing, which is fixed with the help of nuts screwed into threaded parts made at the ends of the rotor on the surface of its hole. The elastic bushing is adjusted, and its stiffness is set with the help of the specified nuts.

EFFECT: technological resources are expanded; efficiency and quality of processing is increased.

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Description

The invention relates to the processing of metals by pressure, in particular to methods of processing by pulse-shock surface plastic deformation (PPD), and can be used for finishing and hardening of cylindrical, screw, and complex surfaces, for example, screw pump pumps, screw surfaces with rounded sinusoidal profile, eccentric journals of shafts, cam surfaces and PK profiles.

A known method and device for static-pulsed surface plastic deformation of shafts or screws of screw pumps, comprising a hammer and a waveguide made in the form of rods of the same diameter, and a deforming tool for processing with interference, mounted on the free end of the waveguide with the possibility of application to it normally to the machined the surface of the static load and the periodic impulse load using the striker and waveguide, while the deforming tool is made in the form of a helical cylindrical th spring, rolled into a ring, the inner diameter of which is less than the diameter of the workpiece by the amount of double interference to ensure static load, while a coil screw coil spring is installed to cover the workpiece, in addition, a coil coil spring coiled into a ring contains a tension device for adjusting static load [1, 2].

The disadvantages of the known method and device are the narrow technological capabilities and structurally complex drive of the deforming device, equipped with mechanisms of static and pulse loading of the tool, in the form of a hydraulic pulse generator, has a low efficiency, high energy consumption. All this increases the cost of processing, reduces productivity, affects the quality of the processing surface, requires complex and lengthy settings.

The objective of the invention is to expand the technological capabilities of PPD hardening of complex surfaces by using a covering tool with deforming elements in the form of turns of a helical coil spring, helically twisted and located on the inner surface of the hollow shaft - the rotor of the electric motor and which allows to improve the quality of the machined surface, increase efficiency and productivity and reduce cost. and energy intensity of the processing process.

The problem is solved using the proposed method of static-pulse hardening with a spring deforming tool of the outer surfaces of the screws and cylindrical shafts, including a message to the workpiece and a multi-element deforming tool of rotational movements around its own axes and longitudinal feed to a multi-element deforming tool, using a multi-element deforming tool containing deforming elements made in the form of coils of a coil spring, vi twisted and enveloping the workpiece, and the housing with a central hole in the form of a stator of a three-phase asynchronous short-circuited electric motor, inside of which a rotor in the form of a hollow shaft is mounted on rolling bearings, and the deforming elements are located in the rotor hole on an elastic sleeve, which is fixed with nuts, screwed into the threaded parts made from the ends of the rotor on the surface of its hole, while adjusting and setting the stiffness of the elastic sleeve using the above-mentioned nuts.

Features of the method and operation of the device are illustrated by drawings.

Figure 1 shows a diagram of the implementation of the proposed method and device for hardening a complex screw surface, a longitudinal section; figure 2 is a view along A in figure 1, an end view; figure 3 is a General side view of figure 1; figure 4 is a section along BB in figure 1.

The proposed method and device that implements it are intended for plastic deformation and hardening of screw and complex profile surfaces (for example, screw pump pumps, screw surfaces with a rounded sinusoidal profile, cylindrical shafts, cam shafts, cam surfaces and PK profiles), the operation of which lies in the fact that the workpiece 1 and the deforming tool 2 report rotational movements V _W and V _And, respectively, while the device with the deforming tool 2 report the movement of the longitudinal feed S _PR , and the creation of interference is ensured by the transverse feed S _pop . The device has deforming elements that inflict numerous blows on the surface of the workpiece, plastically deforming and hardening the outer surface.

For surface pulsed-impact deformation of the workpiece’s work surface, for example, screw pump screw 1 (see Fig. 1), pretreated, for example, by turning, it is fixed in a fixture, for example, in a three-jaw self-centering cartridge with a center tailstock (not shown), and report the rotational movement V _З around its own central axis, and the pulse-impact deforming tool 2 of the device — the longitudinal feed S _PR and the possibility of movement S _POP in the transverse direction to create interference N required for hardening.

Implementing the proposed method, the device consists of a housing 3 made in the form of a stator of a three-phase asynchronous squirrel-cage motor, taken, for example, according to GOST 19523-74, with poles 4 and made of gray cast iron. Inside the stator housing 3, on the rolling bearings 5, a rotor 6 is mounted in the form of a hollow steel shaft.

In the hole of the rotor 6 on the elastic sleeve 7 there are deforming elements 8 in the form of turns of a helical coil spring 2, twisted helically and covering the workpiece 1. The elastic sleeve 7 is made, for example, of polyurethane SKU-7L, rubber, foam rubber and other elastic material. If the sleeve is made of rubber, then during vulcanization, the rubber is firmly connected to the metal turns of a helical cylindrical helical twisted spring 2. The spring 2 is placed in the sleeve 7 with its turns with an outer diameter d so that three quarters of d turns are located in the sleeve 7 and only one fourth part d of the turns is freely located in the hole of the sleeve 7 and protrudes above its inner surface. The elastic sleeve 7 is planted in the hole of the rotor 6 in a tight fit.

From the ends of the rotor 6, the elastic sleeve 7 is fixed with the help of nuts 9, screwed from each end into the threaded parts of the hole of the rotor 6. In addition, the nuts 9 serve not only to fasten and prevent longitudinal displacement of the elastic sleeve in the hole of the rotor, but also for regulation and installation the necessary stiffness of the elastic sleeve 7, affecting and supporting the interference N of the installation of deforming elements.

The hardening force P acting through deforming elements — spring coils — on the workpiece surface 1 is defined by the transverse feed S _POP (see FIG. 4). The proposed method and the design of the device that implements it, which provides for mounting the deforming tool 2 in the shaft hole of the rotor 6 of the electric motor mounted, for example, on the transverse support of the lathe (not shown), allows the deforming elements made in the form of spring coils to bend and make transverse movements A _POP caused by eccentric displacement and the location of certain sections of the machined helical surface.

So, for example, the lateral displacements A _{POP of the} deforming elements 8 when processing the screw left H41.1016.01.001 of the screw pump EVN5-25-1500 will be equal to the eccentricity e ₁ = 1.65 mm, see figure 1. The transition of the contact of the tool 2 with the workpiece 1 from one deforming element 8 to another deforming element causes a pulse-impact plastic deformation of the surface layer of the workpiece.

The rotational motion V _{and the} rotor shaft 6 with deforming elements 8 is transmitted using electric forces induced in the body - the stator of the electric motor, and is the minimum kinematic connection in length and complexity, and eliminates the use of intermediate belt, gear and other gears and reducers, therefore the device has high efficiency.

The hardness of the surface layer, the hardening depth and surface roughness obtained by the proposed method using this device depend on the impact force and the number of impacts per 1 mm ^{2 of the} surface. These parameters, in turn, depend on the peripheral speed of the rotor shaft with deforming elements 8, interference, the size of the deforming elements, their number, speed, the longitudinal feed of the device and the number of passes.

Despite the fact that the rotational speed of the tool V _{And is} not adjustable, since an asynchronous electric motor is used, the device allows you to smoothly adjust the resulting hardening speed. It is known that when the workpiece rotates at a speed of V _З and the tool - V _And in different directions, when the tool covers the workpiece (see Figs. 1-2, 4), the resulting machining speed is equal to the sum of the speeds, and when rotated in one direction, the resulting processing speed is equal to the difference of speeds V _W and V _AND . Therefore, in the latter case, by adjusting the speed of the workpiece V ₃ , the resulting processing speed is smoothly adjusted, at a constant tool speed V _And . Thus, in order to smoothly adjust the resulting hardening speed, it is necessary to turn on the rotation of the workpiece V ₃ and tool V _AND in one direction.

Modes of pulse-impact deformation by the proposed method, implemented by this device, equipped with, for example, a spring of heat-treated steel grade 65G, which is made of wire with a diameter of 2 mm, the diameter of the coil of the spring is d = 35 mm, the number of turns is 48 at a step of 10 mm, screw twisted and three times covers a steel billet (see figure 1), the following: the peripheral speed of the rotor shaft - V _And ≈2.0 ... 4.0 m / s, the peripheral speed of the workpiece - V _З ≈0.05 ... 0.5 m / s, the number of passes - 2 ... 3, the interference - 0.5 ... 1.5 mm.

As a result of pulse-impact plastic deformation of microroughnesses and the surface layer of the proposed method, the surface roughness parameter increases to Ra = 0.08 ... 0.4 μm with the initial value of Ra = 0.8 ... 3.2 μm. The hardness of the treated surface increases by 25 ... 75% with a riveted layer depth of 0.25 ... 2.5 mm. The residual compressive stresses reach 350 ... 750 MPa on the surface.

Pre-treatment of the workpiece: grinding to a roughness parameter value Ra = 0.4 ... 1.6 μm, as well as finishing turning of surfaces with a roughness Ra = 3.2 μm.

The method and device for pulse-impact deformation allows you to create a regular microrelief on the machined complex, including helical, surface, capable of holding lubricants and prolonging the service life of parts during operation.

The method and device for pulse-impact deformation is used in the manufacture of blanks from non-ferrous metals and alloys, cast iron and steel with hardness up to HRC 58 ... 64.

In industrial tests of the method and device installed in the cartridge with an electromechanical drive lathe mod. 16K20FZ, processed the screw blank of the left H41.1016.01.001 screw pump EVN5-25-1500, which had the following dimensions: total length - 1282 mm, length of the screw part - 1208 mm, cross-section diameter of the screw - D ₁ = 27 ^-0.05 mm, eccentricity - e ₁ = 1.65 mm, pitch - t = 28 ^{± 0.01} mm, roughness Ra = 0.4 μm; single-helical screw surface, left direction; material - steel 40X, hardness HB 270-280, weight - 5.8 kg. Processing was carried out using the developed method and device, based on an IM5010 electric motor, model 4АВ132 В6, having a rotor shaft rotational speed n = 750 min ^-1 ; the outer diameter of the rotor shaft is 157.3 mm; the diameter of the hole bored under the tool and the workpiece from 54 mm to 115 mm; length of the housing - stator - 253 mm; the outer diameter of the housing - stator is 261 mm.

Impulse-impact PPD hardening was carried out in the following modes: peripheral tool speed - V _And ≈2.5 m / s; the peripheral speed of the workpiece is V _З ≈0.25 m / s, the number of passes is 3, the interference fit is 0.5 mm, the longitudinal S _PR feed is 1.5 ... 2.0 mm / rev, the hardening force is 170 ... 175 N; the screw diameter changed after processing by 0.02 mm (0.01 mm per side); the depth of the hardened layer was in the range of 0.15 ... 0.20 mm; hardness increase by 25 ... 30%; during processing, the deforming elements were lubricated with a mixture of industrial oil (60%) and kerosene (40%), the surface of the workpiece with kerosene. The values of technological factors (impact frequency, feed rate) were chosen 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 initial roughness parameter Ra = 3.2 μm, achieved - Ra = 0.32 μm; deforming tool - deforming coils made of steel 65G, hardness HRC 63 ... 65, inner radius along the vertices of deforming elements 30.57 mm.

The depth of the hardened by pulse-shock processing of the layer 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 and device, a similar depth of the hardened layer is achieved as a result of short-term pulse-impact impact on the deformation zone of the energy pulse.

The required roughness and accuracy of the helical surface was achieved after T _m = 3.6 min (against T _m ^bases = 10.5 min according to the basic version with traditional rolling of screws on a 1K62 lathe at OAO Livhydromash).

To ensure the required quality and dimensional accuracy of the processing, the main time was 3 times less than when rolling in with a traditional obkatnik. In this case, the depth and microhardness of the hardened layer (white zone) were 0.15 ... 0.20 mm and 8 ... 9 GPa, respectively, with a gradual decrease in microhardness in depth to the initial state - 2.0 ... 2.5 GPa.

The control was carried out by an indicator bracket with an indicator ICh 10 B cells. 1 GOST 577-68. The cumulative error between any non-adjacent steps was not more than 0.1 mm, the clearance when controlling the straightedge of the protrusions forming in diameter was not more than 0.07 mm, which is permissible according to the technical specifications.

Studies of the stress state of the hardened surface layer by pulse-shock processing 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 maximum roughness value achieved during processing by the proposed method is Ra = 0.08 μm, a reduction of the initial roughness by a factor of 6 is possible.

Impulse-impact deformation in the process favorably affects the working conditions. It leads to a more uniform distribution of the load on the deforming elements, facilitates the formation of a hardened surface.

Impulse-impact deformation contributes to better penetration of the cutting fluid (coolant) into the treatment area. When applying a pulsed load, the deforming elements and the deforming surface periodically “rest”, which helps to increase its resistance. Processing under conditions of pulse-impact deformation sharply increases the cooling, dispersing and plasticizing effect of the coolant due to the facilitation of its access to the contact zone of the deforming elements and the workpiece.

The proposed method extends the technological capabilities of pulse-impact treatment by surface plastic deformation, allows you to control the depth of the hardened layer, the degree of hardening and the surface microrelief. At the same time, a structurally simple electric drive of the device that implements the proposed method reduces the cost of processing, increases productivity, improves the quality of the processed surface, does not require complex and lengthy settings.

Information sources

1. RF patent 2324584. IPC V24V 39/04. The method of static-pulsed surface plastic deformation. Stepanov Yu.S., Kirichek A.V., Afanasyev B.I., Fomin D.S., Samoilov N.N., Vasilenko Yu.V., Podzolkov M.G., Selemenev K.F. 2006132948/02, 09/13/06; 05/20/08. Bull. No. 14.

2. RF patent 2325265. IPC V24V 39/04. IPC V24V 39/00. Device for static-pulsed surface plastic deformation. Stepanov Yu.S., Kirichek A.V., Afanasyev B.I., Fomin D.S., Samoilov N.N., Vasilenko Yu.V., Podzolkov M.G., Selemenev K.F. 2006132949/02; 09/13/06; 05/27/08. Bull. No. 15.

Claims (1)

The method of static-pulse hardening by a spring deforming tool of the outer surfaces of the screws and cylindrical shafts, comprising communicating to the workpiece and a multi-element deforming tool rotational movements around its own axes and longitudinal feeding to a multi-element deforming tool, characterized in that they use a multi-element deforming tool containing deforming elements made in the form of turns of a helical coil spring, helically twisted and covering the claw a lead and a housing with a central hole in the form of a stator of a three-phase asynchronous squirrel-cage motor, inside of which a rotor in the form of a hollow shaft is mounted on rolling bearings, and the deforming elements are located in the rotor hole on an elastic sleeve, which is fixed with nuts screwed into the threaded parts made from the ends of the rotor on the surface of its hole, while regulating and setting the stiffness of the elastic sleeve using the above-mentioned nuts.

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