RU2433903C2 - Device for static-pulse hardening - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming, particularly, to surface plastic deformation of shafts with billets with complex screw and complex-shape surface. Proposed device comprises body with central bore, deforming elements and hollow-shaft rotor. Said body is made up of three-phase induction squirrel-cage motor with rotor running in antifriction bearing there inside. Hollow shaft face surfaces have threaded bores. Deforming elements are made up of coils of helical spring coiled to embrace to billet and fitted in rotor bore on flexible sleeve. Flexible sleeve is secured by nuts screwed in rotor threaded bores to adjust rigidity of said sleeve.

EFFECT: expanded performances, higher efficiency and quality.

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Description

The invention relates to the processing of metals by pressure, in particular to the manufacture of tooling for processing by impulse-impact surface plastic deformation (PPD), and can be used for finishing and hardening of cylindrical, screw and complex profile surfaces of shafts, for example, screw pump pumps, screw surfaces with rounded -sinusoidal profile, eccentric shaft necks, 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 the 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 provide a 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, which is characterized by 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 coils of a helical coil spring, helically twisted and located on the inner surface of the hollow shaft-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 device for static-pulsed surface plastic deformation by hardening shafts and blanks with helical and complex surfaces, comprising a housing with a central hole and deforming elements, the device is equipped with a rotor in the form of a hollow shaft, the housing is made in the form of a three-phase asynchronous stator squirrel-cage motor, inside of which a rotor is mounted on rolling bearings, from the ends of which on the surface of the hole threaded parts, deforming elements in the form of turns of a helical coil spring twisted helically with the possibility of covering the workpiece, are located in the rotor hole on the elastic sleeve, while the elastic sleeve is fixed with nuts screwed into the threaded parts of the surface of the rotor hole with the possibility of regulation and installation stiffness of the elastic sleeve.

Design features of the device are illustrated by drawings.

Figure 1 shows a diagram of an implementation of the proposed 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 device is intended for plastic deformation by hardening shafts and workpieces with screw and complex surfaces (for example, screw pump screws, screw surfaces with a rounded sinusoidal profile, cylindrical shafts, eccentric shaft necks, cam surfaces and PK profiles), its operation consists in that the workpiece and the deforming tool are informed by the rotational movements V ₃ and V _And respectively, while the device with the deforming tool is informed by reduction of the longitudinal feed S _PR , and the creation of interference is ensured by the transverse feed S 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 surface being machined, 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.

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 materials. 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 planted with its turns in the sleeve 7 so that three quarters of the coil with an outer diameter d are located in the sleeve 7 and only one fourth d coil is freely in the hole of the sleeve 7 and protrudes above the 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 the deforming elements — spring coils — on the workpiece surface 1 is defined by the transverse feed S _POP . The proposed design of the device and the fastening of the deforming tool 2 in the hole of the rotor shaft 6 of the electric motor mounted, for example, on a transverse support of a lathe (not shown), allows deforming elements made in the form of spring turns to bend and make transverse movements A of the _POP caused by an eccentric the offset and location of some sections of the machined helical surface.

So, for example, the transverse displacements A _{POP of the} deforming elements 8 when processing the screw of the left H41.1016.01.001 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 movement V _{And the} rotor shaft 6 with deforming elements 8 is transmitted using electric forces induced in the stator case 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 depth of hardening and surface roughness obtained using the proposed device depend on the strength of the impact and the number of strokes per 1 mm ² 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, rotation speed, 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, when controlling the speed of the workpiece V _{3, the} resulting machining speed is smoothly regulated, at a constant tool speed V _AND . Thus, in order to smoothly adjust the resulting hardening speed, it is necessary to turn on the workpiece speeds V _W and tool V _AND in one direction.

Modes of pulse-impact deformation for the proposed device, equipped, for example, with a spring from 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, twisted helically 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, interference - 0.5 ... 1.5 mm.

As a result of pulse-impact plastic deformation of microroughnesses and the surface layer of the proposed device, the surface roughness parameter rises to R _a = 0.08 ... 0.4 μm with the initial value of R _a = 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 R _a = 0.4 ... 1.6 μm, as well as finishing turning of surfaces with a roughness R _a = 3.2 μm.

The 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 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, the devices processed the mod installed in the cartridge with an electromechanical drive of a lathe. 16K20F3 screw blank for 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-sectional diameter of the screw - D ₁ = 27 ^-0.05 mm, eccentricity - e ₁ = 1.65 mm, pitch t = 28 ^{± 0.01} mm, roughness R _a = 0.4 μm; single-helical screw surface, left direction; material - steel 40X, hardness HB 270-280, weight - 5.8 kg. The processing was carried out using the developed device, based on the IM5010 electric motor, model 4АВ132В6, having a rotor shaft speed of 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; stator housing length - 253 mm; the outer diameter of the stator housing is 261 mm.

Impulse-impact PPD were conducted in the following modes: peripheral speed of the instrument - 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 R _a = 3.2 μm, achieved - R _a = 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 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 were achieved after T _m = 3.6 min (against T _m ^bases = 10.5 min according to the basic version with the 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 during the control by 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 device is R _a = 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 operating conditions of the device. 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 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 device 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 drive reduces the cost of processing, increases productivity, improves the quality of the machined 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. Application No. 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. Application No. 2006132949/02; 09/13/06; 05/27/08. Bull. No. 15.

Claims (1)

Device for static-pulsed surface plastic deformation by hardening shafts and billets with screw and complex surfaces, comprising a housing with a central hole and deforming elements, characterized in that it is provided with a rotor in the form of a hollow shaft, the housing is made in the form of a stator of a three-phase asynchronous short-circuited electric motor, inside of which a rotor is mounted on rolling bearings, from the ends of which threaded parts are made on the surface of the hole, deforming elements They are made in the form of coils of a helical coil spring twisted helically with the possibility of covering the workpiece and are located in the rotor hole on the elastic sleeve, while the elastic sleeve is fixed with nuts screwed into the threaded parts of the rotor hole surface with the possibility of adjusting and setting the stiffness of the elastic sleeve.

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