RU2430826C2 - Device for surface plastic deformation - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to machine building, particularly, to fine hardening of shafts and screws. Device comprises deforming elements made up of coil spring rings and three-phase induction squirrel-cage motor incorporating stator accommodating hollow-shaft rotor running in rolling bearings therein. Hollow shaft face surfaces have threaded bores. Said rings are fitted in rotor bores and based therein by washers. Washers are provided with ring-orienting grooves and arranged on lateral sides of every ring. Rings with washers are fitted in rotor bores by means of nuts screwed in rotor bore surface thread.

EFFECT: expanded performances, higher efficiency and quality.

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Description

The invention relates to mechanical engineering technology, in particular to hardening processing of workpieces such as shafts and screws of steels and alloys by surface plastic deformation by a multi-element device with a deforming annular spring.

Known three-roller device for rolling in non-rigid shafts, which consists of a housing, a floating holder with rollers, pivotally connected to the housing, and a spring [1]. A fixture, mounted, for example, on a support of a lathe, allows you to neutralize the runout of the surface of the workpiece - the shaft, which does not affect the processing. Several deforming elements of the device allow you to unload the nodes from the unilaterally applied force when rolling non-rigid workpieces.

The disadvantages of the known three-roller device are: narrow technological capabilities, low productivity due to the small point contact spot of the deforming roller elements with the surface to be treated, a small number of deforming elements, low feed, as well as complexity and large design dimensions.

Known rolling device containing a housing with disks, between which are installed deforming elements in the form of turns of a steel coil spring of circular cross section, which has a device for regulating the rolling force [2].

The disadvantages of the known devices are: narrow technological capabilities, the workpiece is subject to unbalanced radial loads, which cause vibrations, leading to a decrease in the accuracy and quality of processing. In addition, a structurally complex drive increases the cost of processing, reduces productivity, degrades the quality of the processing surface, requires complex and lengthy settings.

The objective of the invention is the expansion of technological capabilities, consisting in the fact that the proposed device should increase the roughness parameter of the processed surface, increase its hardness to a considerable depth due to the smoothing effect of a large number of deforming elements, increase productivity by increasing the contact spot of deforming elements with the treated surface and the possibility of application high feeds and regulation of working efforts, as well as reduce cost process and reduce the cost of manufacturing the device due to the compactness and simplicity of the drive design and its integration.

The problem is solved using the proposed device for processing shafts and screw surfaces of screws by surface plastic deformation, containing a body and deforming elements in the form of rings of a steel coil spring of circular cross section, the device is equipped with a rotor in the form of a hollow shaft, from the ends of which on the surface of the holes are made threaded parts, the housing is made in the form of a stator of a three-phase asynchronous squirrel-cage motor, inside of which on rolling bearings with the rotor is mounted, the said rings are installed in the rotor hole and are based on it with washers, which are made with grooves for orienting the rings and are located on the sides of each ring, while the rings with washers are fixed in the rotor hole with nuts screwed into the threaded parts of the surface rotor holes with the ability to control and install interference rings.

Design features of the device are illustrated by drawings.

Figure 1 shows the proposed device for surface plastic deformation with deforming elements in the form of rings of a steel coil spring, a longitudinal section, deforming elements configured for minimal interference and the coil of the spring have a circle shape; figure 2 is a General view from the left along A in figure 1; figure 3 is a General side view, a partial longitudinal section, deforming elements are configured for maximum interference and have the shape of an ellipse; figure 4 is a section bB in figure 1, an annular multi-element deforming spring; figure 5 is a block consisting of an annular spring and two washers located on the sides, a longitudinal section; figure 6 - section bb in figure 5; Fig.7 is a base washer, an end view; Fig.8 is a base washer, side view, a longitudinal section.

The proposed device is used for processing surface plastic deformation (PPD) of the outer surfaces of rotation of the workpieces such as shafts and screws with a large pitch, for example, screws of screw pumps.

The processing is performed on turning, rotary machines with the message of the rotational movement of the workpiece - V _З , for the deforming tool - of the rotational movement - V _And , and the device - the movement of the longitudinal feed S _PR .

The deforming elements of the proposed device are turns 1 of steel of circular cross-section of a coil spring 2, rolled into a ring.

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 hollow shaft of the rotor 6, rings 2 are installed, made of a coil spring, consisting of turns 1, which are deforming elements.

The deforming rings 2 are based in the bore of the rotor shaft 6 using washers 7, which have grooves 8 for orienting the turns of the coil spring 2. The washers 7 are located on the sides of each ring 2. Thus, two washers 7 with the deforming ring 2 constitute a block, from which the deforming tool of the device is recruited. For example, the deforming tool of the device shown in figures 1, 3, consists of three blocks.

The assembled blocks - ring 2 with two washers 7 in the hole of the shaft-rotor 6 - are fixed with nuts 9. The nuts 9 are screwed from each end into the threaded parts of the hole of the shaft-rotor 6. Using the nuts 9, the tightness of the deforming elements of the rings is also adjusted and installed 2.

Preload, i.e. force action on the surface of the deforming springs, in this case, should be understood as half the difference in the diameter of the workpiece, for example, in Fig. 1, this is the diameter D ₁ and the inner diameter d along the vertices of the deforming turns of the ring in a free unloaded state. The deforming elements can be set to a minimum interference, while the spring coils have a shape close to a circle (see figure 1). When you configure the deforming elements to the maximum interference, they turn into an ellipse (see figure 3). In the latter case, the nuts 9 are completely screwed into the hole of the rotor shaft 6.

Surface plastic deformation can be carried out, for example, on a lathe, then the device is mounted on a support (not shown), and the workpiece, for example, screw 10, is fixed in the headstock spindle chuck and is pressed by the center of the tailstock (not shown).

After the workpiece 10 is fixed in the cartridge, the device is led to the free end of the workpiece and using manual longitudinal feed of the caliper, overcoming the resistance of the deforming spring, string the device onto the workpiece, and then tighten the rear center. Installation of the workpiece and device can also be done using a process sleeve (not shown).

Before turning on the machine and the device’s electric motor, the desired machining force is adjusted by turning the nuts 9 with a special key, bringing the washers together 7 and controlling the force value on a scale that, when calibrated, is applied, for example, on the end of the rotor, and the zero mark on the end of the nut (not shown) .

The main movement V ₃ is turned on - rotation of the workpiece 10, then the device’s electric motor, i.e. - V _And , and simultaneously progressive longitudinal feed S _PR .

The essence of the process lies in the fact that during operation of the device, a deforming spring 2, installed with an interference fit relative to the workpiece being machined, covers it. Processing is carried out by turns 1 of spring 2, exerting pressure on the surface of the workpiece. With a certain (working) force in the contact zone between the deforming elements and the workpiece, the stress intensity exceeds the yield strength, resulting in plastic deformation of microroughnesses, the physical and mechanical properties and structure of the surface layer change (for example, microhardness increases or residual stresses arise in the surface layer).

Volumetric deformation of the workpiece is negligible.

The presence of an elastic element, which is a deforming spring 2, provides a constant force of surface plastic deformation at any point on the treated surface.

As a result of plastic deformation of microroughnesses and the surface layer, the surface roughness parameter increases to Ra = 0.1 ... 0.4 μm with the initial value Ra = 0.8 ... 3.2 μm. The surface hardness increases by 30 ... 80% with a riveted layer depth of 0.3 ... 3 mm. Residual compressive stresses reach 400 ... 800 MPa on the surface.

Pretreatment of the part: grinding to a roughness parameter value Ra = 0.4 ... 1.6 μm, as well as finish turning of surfaces with a roughness Ra = 3.2 μm.

The processing of the proposed device is used in the manufacture of billets of non-ferrous metals and alloys, cast iron and steel with a hardness of up to HRC 58 ... 64.

Deforming elements of the device, i.e. spring, made of steel: alloyed ШХ15, ХВГ, 9Х, 5ХНМ, carbon tool U10A, U12A, high-speed R6M5, P9. Hardness of the working surface of coils made of HRC 62 ... 65 steels. The roughness parameter of the working profile of the coil of the spring Ra = 0.32 μm.

The performance of the surface plastic deformation process is determined by the radius of the coil of the deforming spring and the diameter of the wire from which the spring is made.

A device tool with a large radius of the coil of the deforming spring and the diameter of the wire allows processing with a large feed (up to 3 mm / rev), however, in this case, to obtain a high surface quality, it is necessary to create large working forces. The parameters of the deforming spring depend on the value of the allowable working force.

The proposed multi-element device provides a constant contact force of the deforming elements and the work surface and almost does not reduce the error of the previous processing, being a copy.

The change in surface size during processing is associated with crushing of microroughnesses and plastic bulk deformation of the workpiece. Thus, the accuracy of the processed workpiece will depend on its design and the design of this device, processing conditions, as well as on the accuracy of the size, shape and surface quality of the workpiece obtained during processing at the previous transition. The size change depends on the state of the initial surface (see table).

Resizing the surface of the workpiece during processing by the proposed device depending on the roughness of the original surface Pretreatment Method Roughness parameter Ra, mm The size by which the size changes after processing, mm Turning 6.3 0,025 ... 0,065 3.2 0.015 ... 0.045 1,6 0.010 ... 0.025 Shaving with a (wide) cutter 3.2 0.010 ... 0.025 1,6 up to 0.015 Grinding 3.2 0.015 ... 0.035 1,6 0.010 ... 0.020

Moreover, the dimensional accuracy does not change significantly.

Adverse conditions for processing the workpiece near the ends lead to increased plastic deformation of the workpiece in areas of length 3 ... 15 mm. It is most expedient to process the initial surfaces of the 7 ... 11th qualifications.

With surface plastic deformation (PPD), the proposed device practically achieves roughness parameters Ra = 0.2 ... 0.8 μm with the initial values of these parameters 0.8 ... 6.3 μm. The degree of reduction in surface roughness depends on the material, working force or interference, feed, initial roughness, device design, etc.

Processing the proposed device should be carried out so that the desired results are achieved in one pass. Do not use the reverse stroke as a working stroke, as repeated passes in opposite directions can lead to excessive deformation and peeling of the surface layer.

The speed does not significantly affect the processing results and is selected taking into account the requirements of productivity, design features of the workpiece and equipment. Typically, the speed is 30 ... 150 m / min. The value of the processing force is selected depending on the purpose of the processing. The optimal force P (N) corresponding to the maximum endurance limit is determined by the formula:

P = 500 + 1.66 D ₁ ² ,

where D ₁ - the diameter of the workpiece surface.

The flow during surface plastic deformation is 0.2 ... 3 mm / rev. The optimal supply S _e for one deforming element should not exceed 0.1 ... 0.5 mm / rev. The feed for one revolution of the workpiece is determined by the formula:

S _PR = kS _e ,

where k is the number of deforming elements.

The lubricating-cooling liquid during processing is engine oil, a mixture of engine oil with kerosene (50% each), sulfofresol (5% emulsion). Cast iron processing is recommended without cooling.

Three options for the operation of the device for finishing and hardening of external surfaces are possible:

1 - processing in which the workpiece is stationary V _З = 0, and the tool has a working rotation V _And and axial longitudinal feed S _PR ;

2 - processing, in which the workpiece V ₃ rotates, and the tool is stationary V _И = 0 and has an axial longitudinal feed S _PR ; while the spring tension can be changed directly during processing;

3 - processing, in which the workpiece and the tool rotate with speeds respectively V _W and V _And , and the tool additionally has an axial longitudinal feed S _PR .

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 processing speed. It is known that when the workpiece rotates at a speed of V _З and tool V _AND in different directions, when the tool covers the workpiece (see Fig. 1-2), the resulting machining speed is equal to the sum of the speeds, and when rotated in one direction, the resulting machining speed is speed difference V _W and V _AND . Therefore, in the latter case, by adjusting the speed of the workpiece V ₃ , you can smoothly adjust the resulting processing speed, at a constant tool speed V _And . Thus, in order to smoothly adjust the resulting machining speed, it is necessary to turn on the workpiece speeds V _З and tool V _И in one direction.

During industrial testing of the developed device, the workpiece installed in the cartridge with an electromechanical drive on a lathe mod was processed. 16K20F3. The workpiece was a screw left H41.1016.01.001 of the 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 - ⌀27 ^-0.05 mm, eccentricity - 1.65 mm, pitch - 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. The processing was carried out using the developed device, based on the IM5010 built-in electric motor, model 4АВ132В6, having a rotor shaft speed of 1000 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.

PDPs were conducted in the following modes: peripheral tool speed - V _And ≈1.5 m / s; the peripheral speed of the workpiece is V _З ≈1.0 m / s, the number of passes is 3, the interference is 1.2 mm, the longitudinal S _PR 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 initial roughness parameter Ra = 3.2 μm, achieved - Ra = 0.32 μm; deforming tool - wire with a diameter of 2.5 mm from steel 65G, hardness HRC 63 ... 65, diameter of turns - 30 mm, number of turns in the ring - 12, total number of turns in the tool - 36. The depth of the hardened layer is 1.5 ... 2 times higher than with traditional run-in. The required roughness and accuracy of the helical surface were achieved after T _m = 2.9 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 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 showed that the maximum residual stresses are close to the surface, as when chasing, which is favorable for most of the mating parts of mechanisms and machines.

The ultimate roughness value achieved during the processing by the proposed device is Ra = 0.08 μm, a 4-fold decrease in the initial roughness is possible.

Deformation using the proposed device favorably affects the working conditions of the deforming tool of the device. It leads to a more uniform distribution of the load on the deforming elements, facilitates the formation of a hardened surface.

The use of the proposed device promotes better penetration of the cutting fluid (coolant) into the treatment area. The use of the proposed multi-element deforming tool helps to increase the resistance of each deforming element that works separately. Processing under the conditions of the proposed deformation 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 of the deforming elements and the workpiece.

The proposed device extends the technological capabilities of processing PPD, allows you to control the depth of the hardened layer, the degree of hardening and surface microrelief. At the same time, the structurally simple and compact drive of the device reduces the cost of processing, increases productivity, improves the quality of the processed surface, does not require complex and lengthy settings.

Information sources

1. Reference technologist-machine builder. In 2 vols. T.2 / Ed. A.G. Kosilova and R.K. Meshcheryakova. - 4th ed., Revised. and add. - M.: Mechanical Engineering, 1985. S.383-395, Fig. 7.

2. A.S. USSR 1666290 A1, IPC V24V 39/02. Publ. 07/30/1991 - a prototype.

Claims (1)

A device for treating shafts and screw surfaces of screws by surface plastic deformation, comprising a housing and deforming elements in the form of rings of a steel coil spring of circular cross section, characterized in that it is provided with a rotor in the form of a hollow shaft, from the ends of which threaded parts are made on the surface of the hole, the housing made in the form of a stator of a three-phase asynchronous squirrel-cage motor, inside of which a rotor is mounted on rolling bearings, the said rings are installed in the rotor holes and are based in it with washers, which are made with grooves for orienting the rings and are located on the sides of each ring, while the rings with washers are fixed in the rotor hole with nuts screwed into the threaded parts of the surface of the rotor hole with the possibility of regulation and installation tightness of rings.

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