RU2447983C1 - Method of rolling outer helical surfaces - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming, particularly, to rolling of helical surfaces. Rotation is imparted to billet. Rolling device is fed in longitudinal and transverse directions. Proposed rolling device comprises body with crosswise bore and two transverse grooves, two levers with axles and deforming rollers on end of each lever, extra deforming roller and static-pulse loading mechanism for deforming rollers. Axles of said angular two-arm levers are spring-loaded and arranged in body crosswise grooves to reciprocate therein. Arms of said levers are coupled by common axle with aforesaid extra deforming roller. Mechanism for static and pulse loading of deforming rollers comprises hammer and guide. Common axle is fitted on guide free end. Mechanism for static and pulse loading of deforming rollers is secured by lock screw in body crosswise bore to translate in adjustment.

EFFECT: higher efficiency and accuracy.

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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 external helical surfaces.

A known method of rolling screws on machine tools, including a message to the workpiece rotational motion, and a device for rolling in a longitudinal feed movement, using a rolling device containing two disks with central holes, one of which has a L-shaped holder for fixing the device on the machine support, and the other the disk is rigidly attached to the end face of the first disk by means of spacer sleeves and screws, the upper and lower levers, movably mounted one above the other, located between the disks and pivotally connected interconnected by means of an axis mounted at one end of the said levers, two rockers, one of which is mounted rigidly on one lever and the other pivotally on the other lever, deforming elements in the form of deforming rollers, freely rotating on their axes, mounted in pairs on of the two indicated rocker arms and movably mounted between the said disks, a bearing mounted between the disks and mounted on an axis, a load spring and a hammer providing a pulsed action on a free horse upper arm, lower arm in the middle of a simply supported on the outer bearing ring and at its free end, said fixed hydraulic hammer and the spring load, thus creating a permanent provide static load and pulsed load on the deformation elements [1, 2].

The disadvantage of the method and device by which the known method is implemented is its complicated design, large weight and size parameters, and therefore, the high cost of manufacturing, the high cost of additional time for regulation, commissioning, installation, fastening and removal of the workpiece, which reduces processing productivity and the reliability of the design, degrades the manufacturing quality and accuracy of the processing process.

The objective of the invention is to expand the technological capabilities of surface plastic deformation (PPD) processing of external screw surfaces, providing processing by rolling in the screw surfaces of screws with a deep profile and a large step, reducing the weight and size parameters of the equipment used, as well as reducing the cost and auxiliary time for regulation, commissioning, installation, fixing and removing the workpiece, increasing productivity and improving manufacturing quality, ix reliability and accuracy of processing by the use of the device allowing to carry out static and pulsed burnishing.

The problem is solved by the proposed method of rolling in the outer helical surfaces on the machines, including a message to the workpiece for forced rotational movement, and a device containing a body with a transverse hole and two transverse grooves, two levers with rotation axes and with deforming rollers at the end of each lever, as well as a mechanism static and pulsed loading of deforming rollers, containing a firing pin and waveguide, made in the form of rods of the same diameter, and an additional def a rolling roller installed with the possibility of applying to it normally a static load and a periodic impulse load using the striker and waveguide — longitudinal and transverse feeds, moreover, use a device in which the levers are double-arm angled and their rotation axes are placed in the transverse grooves of the housing with the possibility of reciprocating movement and spring-loaded, the other shoulders of the two-shoulder angular levers are connected by a common axis with an additional deforming roller, while I axis is mounted on the free end of the waveguide, and the mechanism of static and pulsed loading deforming rollers is fixed by a set screw in the transverse hole of the housing with the possibility of transverse movement during setup.

The essence of the method is illustrated by drawings.

Figure 1 presents the configuration diagram and the design of the device that implements the proposed method for rolling in the outer helical surfaces on a lathe in the initial position; figure 2 is a left view along A in figure 1; figure 3 is a section along BB in figure 1; figure 4 - processing diagram and design of a device for running in the outer helical surfaces on a lathe in the final operating position.

The proposed method and its implementing device are intended for static-pulse rolling of screw surfaces with a deep profile and a large pitch. When processing the proposed method, the screw blank 1 is informed of a rotational movement V _З , and for a device with deforming elements, transverse S _POP and longitudinal S _PR feed (see figures 1, 4).

A device that implements the proposed method consists of a housing 2 having a strap 3, with which the device is mounted in a tool holder 3 ^T (see figure 3) on a support lathe (not shown).

On the housing 2 on the axles 4 mounted two-arm angular levers 5, the inner corners of which are facing one another. On the shoulders of the levers 5 facing the treatment area, two deforming rollers 6 are installed on the axes, with the possibility of free rotation.

Opposite shoulders of the levers 5, facing the base of the housing, are connected by a single axis 7, on which an additional deformation roller 8 is mounted with free rotation, the axis 7 being located in the plane of symmetry of the deformation rollers 6.

Work turn 8 ^{In the} additional deforming roller 8 is inclined at an angle α to a plane perpendicular to the longitudinal axis of the workpiece, equal to the angle of the thread of the screw workpiece being rolled in. The deformation rollers have a similar design. 6. The hardness of the material of the rolling rollers is higher than the hardness of the material of the workpiece.

Thus, the three deforming rollers are evenly spaced around the circumference relative to the screw blank being rolled in with an axial offset relative to each other equal to P / 3, where P is the thread pitch of the screw blank being rolled in, mm.

The axis 4 of the levers 5 elastically with the help of tension springs 9 are installed with the possibility of movement in the transverse grooves of the housing 2, made symmetrically relative to the plane passing through the axis 7.

The mechanism 10 of the static _PT and pulsed _IM loading of the deforming rollers is fixed with a locking screw 11 in the transverse hole of the housing 2 with the possibility of lateral movement during adjustment. The mechanism of static and pulsed loading of the deforming rollers contains the hammer 12 and the waveguide 13, made in the form of rods of the same diameter. As a mechanism of static and pulsed loading of deforming rollers, a hydraulic pulse generator (not shown) is used [3, 4].

At the free end of the waveguide 13 using a fork 14 on the axis 7 is installed an additional deforming roller 8.

A device that implements the proposed method and is designed to run in the outer helical surfaces, operates in two modes:

- in the mode of static loading of deforming rollers;

- in the mode of static-pulse rolling.

To work in the mode of static loading, the device is installed, for example, on a lathe and works as follows.

The workpiece 1 is installed in a turning chuck, and the device with a strap 3 - in the tool holder of a lathe. In the initial position of the device (see figure 1), the axis 4 of the levers 5 under the action of the springs 9 are pressed against the outer ends of the transverse (perpendicular to the direction of supply S _PR ) grooves of the housing, while the two-arm angular levers 5 are in a diluted state. The springs 9 are selected with a rigidity sufficient for the specified breeding of the levers 5 in the inoperative position of the device. In this case, the gap between the outer diameter of the working turns of the deforming rollers exceeds the outer diameter of the workpiece thread being rolled by 0.3-0.5 mm.

Then the rotary motion V _З is reported to the workpiece, and the transverse feed movement S _POP is provided to the device with the possibility of providing a certain tared force P _ST created by the hydraulic drive of the static and pulsed loading mechanism (not shown) [3, 4], and at the same time, the longitudinal feed motion S _PR , consistent with the rotation speed of the workpiece, i.e. the longitudinal movement of the caliper with the device is set equal to P mm - the step of the thread being rolled by one revolution of the workpiece.

When the tool moves in the indicated direction P _ST, its additional deforming roller 8 begins to interact with the workpiece surface being machined, moving to the left relative to the body. This leads to the displacement (rapprochement) of the axes 4 in the transverse grooves of the casing, the extension of the springs 9 and the rotation of the levers 5. With further movement of the casing with the feed S _POP , deforming rollers 6 interact with the workpiece surface, rolling around the helical surface. Upon reaching a predetermined breaking-in force P _{ST, the} movement of the transverse feed S _{POP is} stopped and processing is carried out only with a longitudinal feed.

Since the hardness of the material of the processing rollers exceeds the hardness of the material of the machined threaded surface of the workpiece, its material at the contact points is plastically deformed and hardened.

To work in the mode of static-pulse rolling, the device is also installed, for example, on a lathe and works as follows.

Static-pulse rolling is carried out by means of static loading and plus impact on deforming rollers. Impulse action is carried out due to the impact of the striker of the hydraulic pulse generator (not shown) at the end of the waveguide, on which an additional deformation roller is mounted, connected by levers to the deformation rollers 6. The impact energy of the striker is transmitted to the additional deformation roller, which is directly mounted on the waveguide. Therefore, upon impact, the additional deformation roller is shifted in the radial direction to the central axis of the workpiece. The deforming rollers 6 will partially absorb the energy of the impact of the striker, due to the fact that part of it will be absorbed by the springs 9. At the same time, the deforming rollers 6 will not affect the workpiece because the levers rotate by an angle relative to the axes 4, moving away from the workpiece, and only at the end of the impact and the return of the additional deforming roller and levers to their original position, the rollers 6 with a certain time shift will have a deforming effect on the workpiece.

After the termination of the impact energy of the impact on the additional deforming roller, it moves in the transverse direction and returns under the action of the springs 9 to its original position, while the deforming rollers 6 make a deforming impact with a certain time shift, returning to their original positions.

Thus, in one hit of the striker on the waveguide, the deforming rollers perform one vibrational movement in the radial direction.

As a result of the impact of the striker on the end of the waveguide in the striker and waveguide, shock and oppositely directed pulses of the same amplitude and duration arise, each of which will act through three deforming rollers on the surface to be treated with a cycle equal to double the duration of the pulses. Having reached the surface to be treated, the shock pulse is distributed on the passing and reflecting. The passing pulse forms the dynamic component of the strain force.

When only static loads P _{ST are} applied to the deforming rollers, their introduction into the surface to be machined occurs at a smaller value, and the tool track on the surface to be machined has minimal dimensions, with a pulsed load P _{IM, the} introduction of deforming rollers into the surface to be machined is large, and the track of deforming rollers on the treated surface has maximum dimensions.

At the end of the rolling release the locking screw 11 and the device is returned to its original position.

The proposed method and device provides the possibility of hardening with full balancing of the rolling forces of non-rigid blanks of screws during cantilever fastening, as well as thin-walled blanks, while increasing the reliability and accuracy of processing.

The proposed method allows to run in the outer screw surfaces in two modes: in the mode of constant static loading of the deforming rollers due to the hydraulic drive, when the hydraulic pulse generator does not work and in the mode of static-pulse rolling.

The proposed method of static-pulse rolling expands the technological capabilities of PPD and allows for the optimal selection of the parameters of hardening treatment of a helical surface.

The levers 5 are able to swing relative to their axles 4 and allow each deforming roller to be constantly in contact with the machined screw surface, as well as have a stable distributed load on each of the rollers, regardless of their location on the screw surface.

The speed of rotation of the workpiece V _Z set depending on the required performance, design features of the workpiece, equipment. Usually the speed is 3 ... 12 m / min.

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 a one-sided application of force and handle non-rigid (non-rigid parts such as shafts with a length to diameter ratio of more than ten, [5]) are considered screws; 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 _{ИМ is} carried out by hitting a striker of a hydraulic pulse generator (not shown) on the end of the waveguide, on which an additional deformation roller is mounted, connected by levers with deformation rollers 6. The transmitted pulse forms a dynamic component of the deformation force, which intensifies the process of surface plastic deformation and strengthens surface layer of the machined helical surface. The ability to rationally use the energy of shock waves is determined by the size of the instrument.

Example. In industrial testing of a workpiece, a screw made of steel 40X with a threaded resistant thread S80 × 10-7h GOST 10177-82, having a thread profile previously cut with a vortex head, was installed in the centers on the 16K20 machine, and the rolling device was installed on the support. The workpieces reported a rotational movement V _З = 12 m / min, and the device - a longitudinal feed S _PR = 10 mm / rev.

The mechanism of static and pulsed loading of the deforming rollers used a hydraulic pulse generator [3, 4] with impact energy A = 250 J, maximum frequency f = 960 min ^-1 and efficiency = 0.74. The values of technological factors (impact frequencies, radii of deforming rollers, the value of the workpiece rotation frequency) 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 _ST ≥25 ... 40 kN; P _MI = 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. 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.

By tests it was found that the productivity of the process increases by 1.8 ... 2 times compared to rolling the thread in the traditional way, for example with one roller, the thread dimensions are stable and correspond to the required accuracy level, the tool resistance is increased by 2.5 ... 3 times, the surface roughness of the thread surface decreases by 1 ... 2 classes.

The cost of manufacturing equipment decreased by half.

Impulse loads created by the proposed method, 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.

To implement the proposed method, a device is used that is not complicated in design and reliable in operation, and the method of rolling in screw surfaces with a device is simple. 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, to reduce the auxiliary time for regulation, adjustment, installation, fixing and removal of the workpiece and to ensure high accuracy.

Information sources

1. RF patent 2337806. C1. IPC B24B 39/04. The method of static-pulse rolling of screws. Stepanov Yu.S., Kirichek A.V., Afanasyev B.I., Fomin D.S., Sotnikov V.I., Samoilov N.N., Zhirkov A.A., Selemenev M.F. Application No. 2007105314/02. 02/12/07; 11/10/2008. Bull. No. 31.

2. RF patent 2337807. C1. IPC B24B 39/04. Device for static-pulse rolling of screws. Stepanov Yu.S., Kirichek A.V., Afanasyev B.I., Fomin D.S., Samoilov N.N., Inozharsky V.V., Romanenko M.V., Selemenev M.F. Application No. 2007105382/02. 02/12/07; 11/10/2008. Bull. No. 31 is a prototype.

3. Kirichek A.V., Lazutkin A.G., Soloviev D.L. Static-pulse processing and equipment for its implementation // STIN, 1999, No. 6. - S.20-24.

4. RF patent 2090342. Lazutkin A.G., Kirichek A.V., Soloviev D.L. Water hammer device for processing parts by surface plastic deformation. 1997. Bull. Number 34.

5. Reference technologist-machine builder. In 2 vols. T.1 / Ed. A.G. Kosilova and R.K. Meshcheryakova. - 4th ed., Revised. and add. - M.: Mechanical Engineering, 1986. S. 224 ... 227.

Claims (1)

A method of rolling in external screw surfaces on machines, comprising communicating a workpiece with forced rotational movement and longitudinal and transverse feed to a rolling device comprising a body with a transverse hole and two transverse grooves, two levers with pivot axes and with deforming rollers at the end of each lever, and the mechanism of static and pulsed loading of the deforming rollers, including the firing pin and waveguide, made in the form of rods of the same diameter, and an additional def a forming roller installed with the possibility of applying to it normally a static load and a periodic impulse load using the striker and waveguide, characterized in that a rolling device is used, the levers of which are double-arm angled, the rotation axes are placed in the transverse grooves of the housing with the possibility of return - translational movement and spring, while the shoulders of the two-shoulder angular levers are connected by a common axis with an additional deforming roller, and the common axis of the mouth pressed on the free end of the waveguide, and the mechanism of static and pulsed loading of the deforming rollers is fixed with a locking screw in the transverse hole of the housing with the possibility of lateral movement during adjustment.

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