RU2347663C1 - Device for static-pulse rolling of shafts - Google Patents

Abstract

FIELD: mechanics.

SUBSTANCE: device comprises two disks with central holes, one of which has L-shaped holder, and the other is rigidly fixed at the end of the first disk, and deforming elements that are movably installed between disks. Deforming elements are arranged in the form of steel helical cylindrical spring turns from circular wire installed at two yokes that embrace processed billet and are installed on two levers. Levers are hingedly connected to each other with the help of axis installed on one end of levers and are movably installed horizontal between disks one above the other. Lower lever middle 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: technological resources are expanded, processing quality is increased, its high quality is achieved 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.

Known three-roller device for rolling in non-rigid shafts, consisting of a holder with rollers, pivotally connected to the housing, which is mounted on the support of the machine [1].

A disadvantage of the known 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 profile radius, which negatively affects the overall dimensions and not always feasible.

A device is known for rolling in non-rigid screws, 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 hole, 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 the disks, in addition, stretch marks - springs are fixed on spacer sleeves [2].

A disadvantage of the known 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 rolling around a wide range of non-rigid shafts with cylindrical surfaces coaxial to the axis and with a displaced axis (eccentrics), screw surfaces of screws with a large pitch, as well as reducing costs, increasing productivity and improving the quality of manufacturing, thanks to the use of a device that allows for static-pulse rolling with a multi-element deforming tool on t m is the machine tool, which makes the preliminary roughing the surface of the workpiece.

The problem is solved by using the proposed device for static-pulse rolling of the shafts, consisting of two disks with central holes, one of which has a L-shaped holder, with which the device is mounted on the support of the machine, and the other disk is rigidly attached to the end of the first disk with using spacer sleeves and screws, and deforming elements movably mounted between the disks, while the deforming elements are made in the form of rounds of a steel coil spring from a wire round about the cross-section mounted on two rocker arms covering the workpiece, the latter mounted one rigidly and the other pivotally on two levers, which, in turn, are pivotally using 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 of the lower lever rests on the outer ring of the bearing mounted between the disks and sitting on the axis, in addition, a hammer is mounted on the other free end of the lower lever, imp acting on the free end of the upper arm, and the load spring.

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

When processing the proposed device, the billet of the shaft is informed of a rotational movement V _З , and for a device 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 arms at an acute angle to the longitudinal axis of the workpiece, equal to the angle of inclination of the coils 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 - using a strap screwed in, 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 lever 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 device has the ability to run various surfaces in two modes: in the mode of constant loading of deforming elements due to the spring, when the hammer does not work and in the mode of pulse-shock rolling.

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 ° from 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.

The operation of the proposed device is as follows.

The device is intended for finishing by surface plastic deformation - rolling in parts such as shafts, for which the device 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 informs the rotational motion V _Z. 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;

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 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 R _a = 0.1 ... 0.4 μm with the initial value of R _a = 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 R _a = 0.4 ... 1.6 μm, as well as finishing turning of surfaces with a roughness R _a = 3.2 μm.

The advantages of the proposed device 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 device, experimental studies of the shaft treatment were carried out, which had the following dimensions: total length - 1292 mm, length of the machined part - 1200 mm, shaft cross-section diameter - с27 ^-0.05 mm, roughness R _a = 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 the proposed 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 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 magnitude of the force of a static tightened tool to the work surface and shock-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]. In the proposed device, 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. 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 1.2 ... 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 device is R _a = 0.08 μm, a possible initial roughness reduction of 4 times is possible.

Impulse loads created by the proposed 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 device is not complicated in design and reliable in operation, and the method of rolling in surfaces of revolution by the 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 device 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. 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. 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)

A device for static-pulse rolling of shafts, containing 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 of the first disk with spacers and screws, and deforming elements, movably mounted between the disks, characterized in that the deforming elements are made in the form of coils of a steel coil spring from a round wire mounted on two covering the workpiece the yoke, the latter are mounted rigidly and the other pivotally on two levers, which are pivotally connected to each other using an axis mounted on one end of the levers, and are movably mounted horizontally between the disks one above the other so that the middle of the lower lever is supported on the outer ring a bearing mounted between the discs and sitting on an axis, in addition, a hydraulic hammer is mounted on the other, free, end of the lower arm, impulse acting on the free end of the upper arm, and a load spring.

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