RU2347664C1 - Method for combined static-impulse processing by surface plastic deformation - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: rotary motion is imparted to billet, and feed motion is imparted along processed billet to device. Device consists of two disks with central holes, one of which has L-shaped holder, and the other one is rigidly fixed at the end of the first disk with the help of spacer bushings and screws, and deforming elements that are movably installed between disks. Static and pulse loads are applied to deforming elements. Deforming elements are arranged in the form of balls and turns of steel helical cylindrical spring from wire of circular section and are serially installed on two levers that embrace the processed billet. Levers are provided with grooves, where balls are installed, and circular grooves with spring semicircles. Levers are hingedly connected to each other with the help of axis installed on one end of levers and are movably installed horizontally between disks one above the other. Lower lever middle rests on external ring of bearing installed between disks and sitting on axis. The other free end of lower lever has hydraulic hammer that affects the free end of upper lever in impulse manner and loading spring fixed to it.

EFFECT: technological resources are expanded, processing quality is increased, its high quality is maintained and prime cost is reduced.

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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 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 disadvantage of this method, implemented by a two-row tool, is the limited application, 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 profile radius, which negatively affects the overall dimensions and is not always feasible , in addition, the method is not sufficiently effective during processing: low efficiency, not sufficiently large depth of the hardened layer, not high enough th power hardening treatment surface and the impossibility of regulating the static and impulsive loadings.

A device for rolling in non-rigid shafts is known, comprising a housing by means of which the device is mounted on a machine support and a holder with deforming elements pivotally connected to the housing, and it is provided with two disks with central holes, one of which is rigidly connected to the housing and the other disk rigidly attached to the end face of the first disk using spacer sleeves and screws, and between the disks is freely installed using three extensions in the form of tension springs holder, carrying deforming elements, with rings, which are inserted into 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 rotation of the holder, it is equipped with a handle located on the periphery, which rests on a roller with an axis fixed between the disks, in addition, the aforementioned stretch marks - springs, mounted on spacer sleeves [2].

The known device 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 the quality of manufacturing, thanks to the use of the proposed device, which allows for static-pulse rolling multi-element deforming tool on the same machine on which the preliminary roughing was performed workpiece surface work.

The problem is solved by using the proposed method of static-pulse rolling of the shafts, 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 support machine, and the other 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 when The deforming elements are subjected to static and pulsed loads and are installed in two rows of two varieties in the form of balls and turns of a steel coil spring from round wire, which are sequentially mounted on two levers enclosing the workpiece, in which respectively the tracks where the balls are located are made and circular grooves, where the half rings of the spring are located, and are fixed with the help of covers, while the levers are pivotally with the help of an axis mounted at one end levers are connected to each other and movably mounted horizontally between the disks 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, impulsing on the free end of the upper arm, and the load spring.

The essence of the method is illustrated by drawings.

Figure 1 presents the processing diagram and the design of the device for implementing the proposed method of combined 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-G in figure 1; in Fig.6 is a section EE in Fig.3; in Fig.7 - section F - G in Fig.3; on Fig - element And in figure 3.

The proposed method is intended for combined 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 rotary motion V _{З is} reported to the shaft blank, and the longitudinal feed S _{PR is} supplied to the device with deforming elements.

A device that implements the proposed method consists of two disks 1 and 2 with central holes, one of which, item 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 of two varieties in the form of balls 6 and turns 7 of a steel coil coil spring of round wire. Sets of deforming elements in the form of balls 6 and turns 7 of the spring half rings are sequentially mounted on two levers 8 and 9 covering the workpiece. One end of the levers 8 and 9 is made semicircular, and the second is straight. In the semicircular part of the levers 8 and 9, which covers the workpiece, are made: respectively, the track where the balls 6 are located, and circular grooves where the turns 7 of the spring half ring are located. Deforming elements in the form of balls 6 can be installed in a separator (not shown), and without it, for example, with support of elements on fluoroplastic inserts 10 and are prevented from falling out by cover 11 fixed to the end of lever 8 by screws 12. Deforming elements in the form turns 7 of the spring, rolled into a half ring, are installed in a circular groove located in the semicircular part of the lever 8, and are held by a cover 13, mounted on the other end of the lever with screws 14, with each coil of the spring individually laid and secured in a groove made in a circle PTO lever recess at an acute angle to the longitudinal axis of the workpiece being treated, equal to the angle of inclination of the turns of the spring, the shape and dimensions of which are counter to the wrap spring, while the depth - not less than the diameter of the spring wire. The coils were secured by known methods, for example, by minting (see Fig. 6), by soldering, welding, mechanically by means of strips and bolts, etc. The fastening of the deforming elements on the lever 9 is similar to their fastening on the lever 8.

The use of spring turns 7 as deforming elements allows each element to be constantly in contact with the surface to be treated and to have a stable distributed load on each of the turns, regardless of their location on the surface to be treated.

Thus, two springs with deforming coils 7, mounted in levers 8 and 9, cover the rolling surface in cross section, evenly spaced relative to each other. 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 8 and 9 are pivotally connected to each other by an axis 15 and are movably mounted horizontally one above the other between the disks 1 and 2, with the middle of the lower lever 9 resting on a support in the form of one or two bearings 16 mounted between the disks and mounted on axis 17. 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 18 is mounted on the free end of the lower lever 9, which impacts the free end of the upper lever 8 and the load spring 19. The hydraulic hammer 18 is mounted on the platform 20, which is mounted on the posts 21 and 22 on the free end of the lower lever 9. The output shaft 23 of the hydraulic hammer 18 carries out a pulse load on the anvil 24, which is mounted on the free end of the upper arm 8. The output shaft 23 of the hammer 18 is mounted and located in the compression spring 19, which constantly acts on the upper arm 8, resting against the area DKU 20.

According to the proposed method, it is possible to run various surfaces in two modes: in the mode of constant static loading of the deforming elements due to the spring 19, when the hammer 18 does not work, and in the static-pulse rolling mode.

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

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

The use of levers 8 and 9 as elements transmitting the forces P _{ST of the} load spring 19 and P _{IM of the} hydraulic hammer 18 to the deforming balls and coils for influencing the surface to be treated, allows these forces to be increased by l ₂ / l ₁ times, where l ₁ and l ₂ - accordingly, the distance between the axis 15 and the longitudinal axis of the workpiece and between the axis 15 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 25, pivotally mounted in disks 1 and 2 and having a handle 26. Cam 25 when the handle 26 is rotated 90 ° relative to the position shown in figure 1, spreads levers 8 and 9 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 carried out in the following sequence. Since the method is intended for finishing by surface plastic deformation — rolling in parts such as shafts, for this, a device that implements the proposed 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 27 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 number of deforming elements - balls;

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 shaft surface by deforming balls, ensuring their constant guaranteed contact with the surface of the part, and the deforming turns self-install, bend and take the form of ellipses. In this case, the levers perform a planetary motion, resting on 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 - balls, are located along the inner diameter D _W , which is smaller than the diameter of the workpiece D _Z , determined by the formula:

D _W = D _W -2h _W ,

where h _W - the tightness of the deforming elements - balls, equal to 0.01 ... 0.5 mm, and the deforming elements - coils, in the free state are installed on the inner diameter D _PR , which is much smaller than the diameter of the workpiece D _Z and D _W , determined by the formula:

D _PR = D _W -2h _PR ,

where h _PR - tightness of deforming elements - coils of the spring, equal to 0.1 ... 1.0 mm

The proposed method, carried out using this device with a two-row combined rolling tool, allows you to process the surface in two transitions: preliminary and finishing. Due to this, a higher quality of processing is achieved. In addition, the first row of deforming elements - balls, rigidly mounted, allows to increase the accuracy of processing. The purpose of the elastic deforming elements - the coil of the spring - 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 balls and coils under the influence of a static load produce a smoothing effect, and under the action of an instantaneous impulse load they 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.

A periodic impulse load P _is carried out using a hammer 18, the output shaft 23 of which acts on the upper arm 8 and then on the deforming balls 6 and the turns of the spring 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 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 (frequency of impacts, diameter of balls, springs and wire from which the deforming tool coils are wound, longitudinal feed size) 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; a possible initial roughness decrease by 4 times is possible.

Impulse loads created by a device that implements 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 is simple to implement, and the device is simple in design and reliable in operation. 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 1.9 ... 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 of the shafts, 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 an L-shaped holder for mounting the device on the machine support, and the other disk is rigidly fixed to the end the first disk with the help of spacer sleeves and screws, and deforming elements movably mounted between the disks, characterized in that they act with static and pulsed loads on the deform The supporting elements, which are installed in two rows, are made of two varieties in the form of balls and coils of a steel coil spring from round wire, sequentially mounted on two levers covering the workpiece, in the latter there are respectively tracks in which the balls and circular grooves are located, in which the half rings of the coil spring are located and secured with covers, while the levers are pivotally connected to each other using an axis mounted on one end e levers, and are movably mounted horizontally between the disks 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, and a hammer is mounted on the other, free, end of the lower lever, impulse acting on the free end of the upper lever, and load spring.

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