RU2347662C1 - Method for static-impulse processing of shafts - 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 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 turns of steel helical cylindrical spring from wire of circular section and are serially installed on two yokes that embrace the processed billet. Yokes are installed on two levers, which 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), as well as screws, for example, screw pumps with a large pitch.

There is a known method and a three-roller device for rolling in non-rigid shafts that implements it, consisting of a holder with rollers pivotally connected to a body that is mounted on a machine support [1].

The disadvantage of this method and device is the limited application, narrow specialization (only for cylindrical surfaces) 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 not always feasible.

A known method and device that implements it for rolling in non-rigid screws, comprising a housing, with which the device is mounted on a machine support, 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 with the case, and the other disk is rigidly attached to the end face of the first disk with spacer sleeves and screws, and a holder carrying a deform is freely installed between the disks with the help of three stretch marks in the form of tension springs bearing 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 rotation of the holder, 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 springs are fixed on spacer sleeves [2, 3].

The disadvantage of this method and device is the narrow specialization and the inability to handle screws with other sizes, the inability to adjust 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 a wide range of non-rigid shafts with cylindrical surfaces, coaxial axis and with a displaced axis (eccentrics), screw surfaces of screws with a large pitch, as well as reducing costs, increasing productivity and improving manufacturing quality through the use of the proposed a method that allows for static-pulse rolling with a multi-element deforming tool on the same machine on which preliminary roughing of the surface of the workpiece was carried out.

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 impulse loads and are made in the form of rounds of a steel coil spring from a round wire mounted on two rocker arms covering the workpiece, the latter mounted rigidly and the other articulated on two levers, which, in turn, pivotally with the help of an axis mounted on one end of the levers, connected to each other and movably mounted horizontally between the disks one above the other so that the middle lower p the 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 acts on the free end of the upper lever, and a load spring.

The essence of the method is illustrated by drawings.

Figure 1 presents the processing diagram and the design of the 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-G in figure 1; in Fig.6 - element E in Fig.1, which shows the pairing of deforming elements fixed in the beam, with the workpiece.

The proposed method is intended for static-pulse rolling of non-rigid shafts having cylindrical surfaces, coaxial axes and with a displaced axis (eccentrics), as well as screws with a large pitch of a wide range.

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 machine support (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 coils 6 of a steel coil spring from round wire mounted on two rocker arms 8 and 9 that cover the workpiece 7. For this purpose, the rocker arms 8 and 9 are made in the form of half arcs, on the inner surface of which coils 6 of the spring are attached . The coils are located in the grooves, which are made in the rocker arms at an acute angle to the longitudinal axis of the workpiece, equal to the angle of inclination of the coil of the spring. The shape and dimensions of the grooves are reciprocal turns of the spring, and their depth is greater than the diameter of the spring wire. The fastening of the turns can be carried out by chasing (see Fig. 6) or mechanically - with the help of a bracket screwed with screws, however, rigid fastening, for example, by welding or soldering, is preferable and allows to obtain a stable processing quality.

One of the rockers, for example, 8 is mounted rigidly using the axis 10 and the pin 11, for example, on the lower arm 12, and the other rocker 9 is pivotally mounted using the axis 13 on the upper arm 14.

The beam 9 has the ability to swing about its axis 13. The beam 9 with deforming elements in the form of turns of the spring 6 serves as a clamping unit, and the beam 8 assembly with deforming turns serves as a guide unit. This allows each rocker with turns to be constantly in contact with the work surface and have a stable distributed load on each of the turns, regardless of their location on the work surface.

Thus, two springs with deforming coils 6 cover the rolling surface in cross section, evenly spaced, relative to each other. With this arrangement, with the condition of rocking one rocker arm, the coils well track the rolling surface, moving the levers relative to the disks by means of the lower rocker arm, which serves as a guide assembly.

The levers 12 and 14 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 arm 12 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 running-in surfaces having an eccentricity.

A hydraulic hammer 18 is mounted on the free end of the lower arm 12, which acts on the free end of the upper arm 14 and the load spring 19. A hydraulic hammer 18 is mounted on a platform 20, which is mounted on the posts 21 and 22 on the free end of the lower arm 12. 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 14. The output shaft 23 of the hammer 18 is mounted and located in the compression spring 19, which constantly acts on the upper arm, resting against the area adku 20.

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

The shock-pulse rolling mode 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.

To install and remove the load on the workpiece being processed, a cam 25 is pivotally mounted in the disks 1 and 2 and has a handle 26. The cam 25, when the handle 26 is rotated 90 ° relative to the position shown in Fig. 1, pushes the levers 12 and 14 and breaks the contact deforming turns with the workpiece, freeing it 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, the device that implements this 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 of the rotational movement of the Uz. 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 reports a longitudinal feed S _np in one direction, which is determined by the formula:

S _PR = kS ₁ ,

where k is the number of deforming 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 rocker arms leverage on the surface of the shaft, providing constant guaranteed contact deforming coils with the surface of the part. The levers perform a planetary motion, resting on one end on a fixed support - bearings, if an eccentric shaft is being machined. Disks perceive axial forces arising during processing from levers, thereby locating deforming turns normally to the axis of the workpiece.

The essence of the process lies in the fact that the deforming turns of the tool are installed according to the inner diameter D _And , which is less than the diameter of the workpiece D _Z , determined by the formula:

D _AND = D _W -2h,

where h is an interference fit of 0.01 ... 0.5 mm.

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. 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 rises to Ra = 0.1 ... 0.4 μm with the initial value Ra = 0.8 ... 3.2 μm. The surface hardness increases by Z0 ... 80% with a riveted layer depth of 0.3 ... 3 mm. Residual compressive stresses reach 3 50 ... 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 hammer 18, the output shaft 23 of which acts on the upper lever 14 and then through the rocker 9 to the deforming coils of the spring 6. 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 - 1292 mm, length of the machined part - 1200 mm, shaft cross-section diameter ⌀27 ^-0.05 mm, roughness Ra = 0.4 μm; material - steel 18HGT GOST 4543-74, hardness HB 207-228, weight - 5.8 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, the diameter of the spring and wire from which the deforming tool coils are wound, the value of the longitudinal feed) 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 mating 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 1.2 ... 1.4 times greater than the depth of the riveted layer, which is consistent with the theory of surface plastic deformation.

The ultimate roughness value achieved during processing by the proposed method is R _a = 0.08 μm, a reduction of the initial roughness by 4 times is possible.

The impulse loads created by the device favorably affect the working conditions of the tool. The imposition of oscillatory motion leads to a more uniform distribution of the load 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 vibration is applied, 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 easy 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 processing productivity by 1.5 ... 2.0 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. P.387, Fig. 6.

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. 2 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. 2.

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 using spacer sleeves and screws, and deforming elements movably mounted between the disks, characterized in that they carry out the action of static and pulse loads on deforming elements made in the form of coils of a steel coil spring from a round wire mounted on two rocker arms covering the workpiece, the latter are mounted rigidly and the other pivotally on two levers that are pivotally connected to each other using an axis mounted on one end of the levers, 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 acting on the axis, in addition, on the other, free, end of the lower lever, a hydraulic hammer is mounted, which impulse acts on the free end of the upper lever, and a load spring.

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