RU2347666C1 - Method of static-impulse rolling - Google Patents

Abstract

FIELD: mechanics.

SUBSTANCE: rotary motion is imparted to blank, and feed motion is imparted along processed blank to device. Device comprises two disks with central holes, one of which has L-shaped holder, and other disk is rigidly fixed to the end of the first disk with the help of spacer bushings and screws, and deforming elements that are movably installed between disks. Deforming elements are arranged on the form of steel helical cylindrical springs turns from circular wire, which are movably installed on two levers that embrace the processed blank. At that every spring freely rotates in axes and rests on at least two press rollers, which are installed in bearings of covers fixed on the ends of specified levers. Levers are hingedly connected to each other with the help of axis installed at one end of levers, and are movably installed horizontally between disks one above another. With its middle lower lever rests on external ring of bearing installed between disks and sitting on axis. On the other free end of lower lever there are hydraulic hammer that affects free end of upper lever in pulse manner and loading spring.

EFFECT: higher efficiency of processing, accuracy and quality of processing.

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Description

The invention relates to the processing of metals by pressure, in particular to the processing of surface plastic deformation (PPD) of non-rigid shafts with cylindrical surfaces, coaxial to the axis and with an offset axis (eccentrics).

There is a method of rolling in the outer cylindrical surfaces with a two-row tool, in which the first row of deforming elements - rollers - is mounted on an elastic mandrel, and the second row of rollers is mounted on a rigid mandrel, while the separator with rollers moves during operation along the axis by pulses [1].

The disadvantages of this method, implemented by a two-row tool, are the limited use, narrow specialization and low productivity, while to obtain high quality it is necessary to create large working forces, and this requires the use of rollers with a large radius of the profile, which negatively affects the overall dimensions and is not always feasible , in addition, the method is not sufficiently effective: low efficiency, not sufficiently large depth of the hardened layer, not sufficiently high degree of rochneniya treated surface and the impossibility of regulating the static and impulsive loadings.

A known method and a device implementing it for rolling in non-rigid shafts, comprising a housing, with which the device is mounted on a support of a lathe, and a holder with deforming elements, pivotally connected to the housing, and it is equipped with two disks with central holes, one of which is rigidly connected to case, and the other disk is rigidly attached to the end face of the first disk using spacer sleeves and screws, and between the disks is freely mounted using three stretch marks in the form of tension springs holder, carrying forming elements, with rings that are inserted in the end grooves of the holder and axially limit the deforming elements freely located in the groove of the holder’s opening, while to prevent the holder from rotating, it is equipped with a handle located on the periphery, which rests on a roller with an axis fixed between disks, in addition, the mentioned stretch marks - springs are fixed on spacer sleeves [2].

The known method is characterized by limited technological control capabilities in creating heterogeneous hardened layers, regular microrelief of the treated surface, and the inability to control the rolling force, which determines the depth of the hardened layer and the degree of hardening.

The objective of the invention is to expand the technological capabilities of the tool by providing processing by rolling in non-rigid shafts with cylindrical surfaces, coaxial to the axis and with a displaced axis (eccentrics), as well as reducing costs, increasing productivity and improving manufacturing quality through the use of static-pulse rolling with a multi-element deforming tool.

The problem is solved by the proposed method of static-pulse rolling, including a message of the rotational movement of the workpiece and the feed movement along the workpiece to a device consisting of two disks with central holes, one of which has a L-shaped holder, with which the device is mounted on the machine support, and another disk is rigidly attached to the end face of the first disk using spacer sleeves and screws, and deforming elements movably mounted between the disks, while the deforming elements applied in the form of coils of steel coil cylindrical springs from round wire, which are movably mounted on two levers covering the workpiece so that the longitudinal axes of the springs and the workpiece are parallel, with each spring freely rotating on the axes and supported by at least two pressure rollers, which are mounted in bearings in caps mounted on the ends of the above-mentioned levers, the levers being pivotally connected to each other by means of an axis mounted at one end of the levers and movably mounted horizontally between the discs, one above the other so that the middle of the lower lever rests on the outer ring of the bearing mounted between the disks and sitting on the axis, in addition, on the other free end of the lower lever are fixed: a hammer, which impulse acts on the free end of the upper lever, and the load spring.

The essence of the method is illustrated by drawings.

Figure 1 shows the processing diagram and design of a multi-row device for static-pulse rolling of non-rigid shafts on a lathe, a longitudinal section along AA in figure 2; figure 2 is a top view along D in figure 1; figure 3 is a section along BB in figure 1; figure 4 is a right side view in figure 1; figure 5 is a cross section along G-D in figure 1.

The proposed method is intended for static-pulse treatment by surface plastic deformation of non-rigid shafts having cylindrical surfaces, coaxial to the axis and with an offset axis (eccentrics).

When processing according to the proposed method, the shaft blank is reported with a rotational motion V _З , and for a device that implements this method, with deforming elements, a longitudinal feed S _PR .

The device consists of two disks 1 and 2 with central holes, one of which, pos. 1, has a L-shaped holder 3, with which the device is mounted on a support of a lathe (not shown). Another disk 2 is rigidly attached to the end face of the first disk 1 using spacers 4 and screws 5.

The deforming elements are made in the form of turns 6 of a steel coil spring 7 of round wire. The deforming springs 7 are movably mounted on two arms 9 and 10 covering the workpiece 8. The number of deforming springs 7 depends on the dimensions of the workpiece 8, since the longitudinal axes of the springs and the workpiece are parallel. Each spring freely rotates on the axes 11, which are located at the ends of the spring and are installed in the covers 12, while the latter are fixed on the levers 9 and 10. The axles 11 are made, for example, of fluoroplastic, to prevent the spring from falling out when the device is not in working condition, and allow the radial movement of the deforming springs.

In the work according to the proposed method, each deforming spring 7 is supported by at least two pressure rollers 13, which are installed in the bearings 14 in the covers 12. The axis of rotation of the rollers 13 are parallel to the axis of the workpiece 8. In the design of the device shown in figures 1-5 , plain bearings in the form of bushings made of fluoroplastic are used, however, bimetallic bushings according to GOST 24832-81, bushings from sintered materials according to GOST 24833-81, as well as rolling bearings can be used as bearings.

The levers 9 and 10 have one end of a semicircular shape, and the second is straight. On the semicircular part of the levers 9 and 10, which covers the workpiece, are fixed from the ends by screws 15 of the cover 12, in which the deforming springs 7 and pressure rollers 13 are installed.

Using the coils 6 of the spring 7 as deforming elements allows each element to constantly be in contact with the work surface and have a stable distributed load on each of the coils, regardless of their location on the work surface.

Thus, springs 7 with deforming coils 6, pivotally mounted in levers 9 and 10 with the possibility of rotation relative to their own longitudinal axis parallel to the longitudinal axis of the workpiece, are uniformly located in the circumferential direction relative to each other and cover the rolling surface in cross section. With this arrangement, with the condition of the possibility of independent planetary movement of the levers relative to the disks, the turns well track the rolling surface.

The levers 9 and 10 with their semicircular ends are pivotally connected to each other by the axis 16 and are movably mounted horizontally one above the other between the disks 1 and 2, while the middle lever 10 rests on the support in the form of one or two bearings 17 mounted between the disks and mounted on the axis 18. This support serves to absorb the load of the torque and reduce the friction force when moving the levers in their planetary movement between the disks at the time of rolling the surfaces of the workpiece having an eccentricity.

A hydraulic hammer 19 is mounted on the free end of the lower lever 10, which impacts the free end of the upper lever 9 and the loading spring 20. The hydraulic hammer 19 is mounted on the platform 21, which is mounted on the posts 22 and 23 on the free end of the lower lever 10. The output shaft 24 of the hydraulic hammer 19 carries out a pulse load on the anvil 25, which is mounted on the free end of the upper arm 9. The output shaft 24 of the hammer 19 is mounted and located in the compression spring 20, which constantly acts on the upper arm 9, resting against the area adku 21.

The proposed method and device have the ability to run in various surfaces in two modes: in the mode of constant loading of the deforming elements due to the spring 20, when the hammer 19 does not work, and in the pulse-shock rolling mode.

The shock-pulse rolling mode expands the technological capabilities of the method and makes it possible to optimally select the parameters of hardening surface treatment.

To change the compression value of the spring and, accordingly, the pressure change on the turns in the static rolling mode, it is enough to change the distance l _P or put another spring with the necessary rigidity.

The use of levers 9 and 10 as elements transmitting the forces P _{ST of the} load spring 20 and P _{IM of the} hydraulic hammer 19 to the deforming coils for influencing the surface being treated allows these forces to be increased by l ₂ / l ₁ times, where l ₁ and l ₂ are the distances, respectively between the axis 16 and the longitudinal axis of the workpiece 8 and between the axis 16 and the axis of the output shaft of the hammer.

To install and remove the load on the workpiece, which is necessary when changing it, serves as a cam 26, pivotally mounted in discs 1 and 2 and having a handle 27. Cam 26 when the handle 27 is rotated 90 ° relative to the position shown in figure 1, spreads levers 9 and 10 and interrupts the contact of deforming elements with the workpiece, freeing the latter from the action of the load.

Work on the proposed method is as follows.

The method is intended for finishing by surface plastic deformation — rolling in parts such as shafts, for which a device implementing the method is installed, for example, in the tool holder of a lathe and a special elongated rotating center of the tailstock (not shown) is passed through the central hole of the disks. The billet of the shaft is fixed in the spindle chuck of the headstock and is pressed by the elongated center of the tailstock. The workpiece of the processed shaft is informed by a rotational motion V _З. The speed of rotation of the workpiece is set depending on the required performance, design features of the workpiece, equipment. Typically, the speed is 3 ... 8 m / min. The device informs the longitudinal feed S _PR in one direction, which is determined by the formula:

S _PR = kS ₁ ,

where k is the total number of deforming coil elements;

S ₁ - the optimal feed to one deforming element is taken no more than 0.01 ... 0.08 mm / rev.

In the process of processing, the levers are guided along the surface of the shaft blank by deforming coils of springs, which rotate during rolling from the workpiece, providing constant guaranteed contact with the surface being processed due to pressure rollers that transmit the forces P _ST and P _IM acting on the levers, while deforming coils self-install, bend and take the form of ellipses. The levers perform a planetary motion, resting at one end on a fixed support - bearings, if the eccentric shaft surface is machined.

The axial forces arising during processing are perceived through the levers by disks.

The essence of the process lies in the fact that the deforming elements - coils are installed according to the inner diameter, which is much smaller than the diameter of the workpiece D ₃ , by a double value of the interference equal to 0.1 ... 1.0 mm.

The proposed method, carried out using a multi-row tool, allows you to process the surface, combining preliminary, semi-finishing and finishing transitions. Due to this, a higher quality of processing is achieved. In addition, the first (relative to the direction of the longitudinal feed S _PR ) rows of deforming elements - coils can improve the accuracy of processing, and the last rows of coils of springs - to create constant conditions for the deformation of microroughnesses.

Due to the interference, the part of the coil in contact with the workpiece is shifted in the radial direction, and the coil turns from a cylindrical to an ellipse, i.e. deforming elements - coils self-install (“float”) in the radial direction.

Deforming coils under the influence of a static load produce a smoothing effect, and under the action of an instantaneous impulse load plastically deform the surface to be treated.

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. 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 advantages of the proposed method are: reducing the error of the previous processing; multi-element device allows for multi-pass processing, due to which a higher quality of processing is achieved; allows you to unload the machine components from unilateral application of force and handle non-rigid shafts; the formation of a certain macro- and microgeometric shape of the treated surface, a decrease in the roughness parameter — smoothing of the surface, a change in the structure of the material due to surface hardening, and the creation of a certain stress state — all this favorably affects the wear resistance.

The periodic impulse load P _is carried out using a hydraulic hammer 19, the output shaft 24 of which acts on the upper arm 9 and then on the deformation coils 6 of the springs 7. The transmitted pulse forms a dynamic component of the deformation force, which intensifies the process of surface plastic deformation and strengthens the surface layer of the processed surface. The ability to rationally use the energy of shock waves is determined by the size of the instrument.

Example. To assess the quality parameters of the surface layer hardened by the proposed method, experimental studies of the shaft processing were carried out, which had the following dimensions: total length - 1290 mm, length of the machined part - 1230 mm, shaft cross-section diameter ⌀27 ^-0.05 mm, roughness R _a = 0.4 μm; material - steel 18HGT GOST 4543-74, hardness HB 207-228, weight - 5.9 kg.

Processing was carried out on a mod screw-cutting machine. 16K20 using a multi-row device with a hydraulic hammer mod. DON UPI with Kar PTI with impact energy A = 250 J, maximum frequency f = 960 min ^-1 and efficiency = 0.47. The values of technological factors (the frequency of impacts, the diameter of the spring and the wire from which the deforming tool coils are wound, the longitudinal feed value) were chosen in such a way as to provide a 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 and impact-pulse load was P _article ≥25 ... 40 kN; P _them = 255 ... 400 kN. The depth of the hardened layer by static-pulse processing is 3 ... 4 times higher than with traditional hardening.

The hardened layer during traditional static processing is formed under long-term action of large static forces [3-5].

According to 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 in the proposed static-pulse processing 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. 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 1.3 ... 1.5 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 R _a = 0.08 μm, it is possible to reduce the initial roughness by 3 ... 4 times.

Impulse loads created by a device operating according to the proposed method, favorably affect the working conditions of the tool. The imposition of a pulse load leads to a more uniform distribution on the deforming elements of the tool, causes additional cyclic movements of the contact surfaces of the tool and the workpiece, facilitates the formation of a hardened surface. Impulse loads contribute to better penetration of the lubricant into the treatment area. When applying load fluctuations, the deforming surface of the tool periodically "rests", which helps to increase its resistance. Processing under pulsed loads dramatically increases the efficiency of the cooling, dispersing and plasticizing action of the lubricant due to the facilitation of its access to the contact zone between the tool and the workpiece.

The proposed method of rolling in surfaces of revolution using a multi-row device is simple to implement. The layer structures obtained on the surface of the hardened billet have increased hardness and, accordingly, wear resistance and resistance to fatigue failure.

Using the proposed method allows to increase the processing productivity of 2.0 ... 2.5 times and to ensure high accuracy.

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.392-393, Fig. 14.

2. RF patent No. 2268134, IPC V24V 39/00. Floating device for rolling in non-rigid screws. Stepanov Yu.S., Kirichek A.V., Samoilov N.N., Afanasyev B.I., Katunin A.A., Fomin D.S. Application 2004128667, 09/27/2004; 01/20/2006. Bull. No. 02 is a prototype.

3. RF patent No. 2268135, IPC V24V 39/00. The method of running in non-rigid screws. Stepanov Yu.S., Kirichek A.V., Samoilov N.N., Afanasyev B.I., Katunin A.A., Fomin D.S. Application 2004128668, 09/27/2004; 01/20/2006. Bull. No. 02.

4. RF patent No. 2275288, IPC V24V 39/04. The covering deforming tool. Stepanov Yu.S., Kirichek A.V., Samoilov N.N., Afanasyev B.I., Fomin D.S. Application 2004131325/02, 10.26.2004; 04/27/2006. Bull. No. 12.

5. RF patent No. 2275289, IPC V24V 39/04. Method of surface plastic deformation by female rings. Stepanov Yu.S., Kirichek A.V., Samoilov N.N., Afanasyev B.I., Fomin D.S. Application 2004131340, 10.26.2004; 04/27/2006. Bull. No. 12.

Claims (1)

The method of static-pulse rolling, including the message of the rotational movement of the workpiece and the feed movement along the workpiece, to a device consisting of two disks with central holes, one of which has an L-shaped holder, with which the device is mounted on a machine support and the other disk is rigidly fixed to the end face of the first disk using spacer sleeves and screws, and deforming elements movably mounted between the disks, characterized in that the deforming elements are made in the form of steel coils coil cylindrical springs of round wire, which are movably mounted on two levers surrounding the workpiece so that the longitudinal axes of the springs and the workpiece are parallel, each spring freely rotates on the axes and rests on at least two pressure rollers that are mounted in bearings in covers fixed to the ends of said levers, the levers being pivotally connected to each other by means of an axis mounted at one end of the levers, and movably mounted horizontally between the disk E above one another so that the middle of the lower arm rests on the outer bearing ring mounted between the disks and is seated on an axle, in addition, at the other, free, end of the lower arm are fixed hydraulic hammer, pulse acting on the free end of the upper arm and loading the spring.

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