RU2337806C1 - Static-pulse method for rolling screws - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: rotatory motion is imparted to work piece, and rolling device is moved longitudinally. The rolling device used has two discs with central openings, deforming elements, upper and lower arms, two balancing levers and a loading spring and hydraulic hammer fixed at the free end of the lower arm. One of the discs has an inverted L-shaped holder for holding the device to the machine slid, while the other disc is rigidly fixed to the butt-end of the first disc by spacers and screws. The deformation elements are movably installed between the above mentioned discs. The upper and lower arms movably installed one over the other, are located between the discs and are hinged to each other by an axle, fixed on one end of the above mentioned arms. One of the balancing levers is rigidly fixed on one arm, and the other is hinged to the other arm. Between the discs there is a bearing. The hydraulic hammer provides for pulsed effect on the free end of the upper arm. The deforming elements are made in form of deformation rollers, freely rotating on their axes, mounted in pairs on the two balancing levers. The lower arm at the middle rests on the bearing collar.

EFFECT: more technological capabilities; increased output and improved quality of objects.

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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 screws, shaft eccentrics, for rolling complex cam surfaces and PK profiles.

A known method of rolling in non-rigid shafts with a three-roller device, consisting of a holder with rollers, pivotally connected to a housing that is mounted on a machine support [1].

The disadvantage of this method 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 weight and size parameters and not always feasible.

A known method for rolling in non-rigid screws, mainly with a large step, in which rotational movement is reported to the workpiece, and a longitudinal feed movement is transmitted to a deforming tool comprising a housing and a holder with deforming elements movably connected to the housing, wherein rolling is carried out by several deforming elements, this tool is equipped with two disks with central holes, one of which is rigidly connected to the body, and the other disk is rigidly attached to the end face the first disk with the help of spacer sleeves and screws, while between the disks, a holder carrying deforming elements with rings that are inserted into the end grooves of the holder and axially limit the deforming elements freely located in the trough holes of the holder, while to prevent rotation of the holder, it is equipped with a handle located on the periphery, which is supported by a roller with an axis fixed between the disks, in addition, the mentioned LCD - springs are fixed on spacer sleeves [3].

The disadvantage of this method [3] and device [2] is the narrow specialization and the inability to handle other sizes of screws, 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 a rolling treatment of screw surfaces of screws with a large pitch, as well as a wide range of cylindrical surfaces, coaxial to the axis, and with an offset axis (eccentrics), for channel screw surfaces having a different diameter, pitch and diameter of the circumference , for rolling complex cam surfaces and for rolling in PK profiles, as well as reducing costs, increasing productivity and improving the quality of cooking through the use of the proposed method, which allows for static-pulse rolling on the same machine on which the preliminary roughing of the helical surface of the workpiece was carried out.

The problem is solved by using the proposed method of rolling screws on the machines, including a message to the workpiece rotational motion, and the rolling device - the movement of the longitudinal feed, using a rolling device containing two disks with central holes, one of which has a L-shaped holder for fixing the device on the support of the machine, and the other disk is rigidly attached to the end face of the first disk by means of spacers and screws, the upper and lower levers, movably mounted one above the other, located between the disks and pivotally connected to each other by means of an axis mounted on one end of the said levers, two rocker arms, 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 two said rocker arms and movably mounted between said disks, a bearing mounted between disks and mounted on an axis, a load spring and hydraulic hammers Providing pulsed effect on the free end of the upper arm, the 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.

The essence of the method is illustrated by drawings.

Figure 1 presents the processing diagram and the design of the device that implements the proposed method for static-pulse rolling non-rigid screws 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 rolling of screws with a large pitch, a wide range of cylindrical surfaces, coaxial to the axis, and with a displaced axis (eccentrics), for channel screw surfaces having different diameters, pitch and diameter of the circumference, for rolling complex cam surfaces and for rolling in PK profiles. When processing according to the proposed method, the screw workpiece is informed of a rotational motion V _З , and for a device with deforming elements, a longitudinal feed S _{PR is} reported.

A device that implements the proposed method consists of two disks 1 and 2 with central holes, one of which, pos. 1, has an 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 deforming rollers 6, which rotate freely on their axes 7. The deforming rollers 6 are mounted in pairs on two rockers 8 and 9, while the rocker 8 is rigidly mounted using the axis 10 and the pin 11 on the lever 12, and the other rocker 9 pivotally mounted using the axis 13 on the lever 14.

Each of the rocker arms 8 and 9 has two grooves in which there are two rolling rollers 6 installed on the landing with a clearance on the axles 7. The axles relative to the levers are fixed by discs 1 and 2.

The beam 9 has the ability to swing about its axis 13. The beam 9 with the deforming rollers serves as a clamping unit, and the beam 8 in combination with the deforming rollers serves as a guide unit. This allows each roller to be constantly in contact with the machined screw surface and have a stable distributed load on each of the rollers, regardless of their location on the screw surface.

Thus, four rollers cover the rolling surface, evenly spaced relative to each other. With this arrangement, with the condition of rocking one rocker arm, the rollers well track the rolling surface of almost any profile, 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 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 an axis 17. This support serves to absorb the load of the torque and reduce the friction force when moving the levers in their planetary motion between the disks at the time of running in of any 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 in the area adku 20.

The proposed method is applicable for rolling various surfaces in two modes: in the mode of constant loading of the deforming rollers due to the spring when the hammer is not working and in the pulse-shock rolling mode when the hammer is working.

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 amount of compression of the spring and, accordingly, change the pressure on the rollers 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 from the workpiece, 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 rollers with the workpiece, freeing it from the action of the load.

Processing the proposed method is as follows.

The method is intended for finishing by surface plastic deformation — rolling in parts such as screws, for example, screws with a channel screw surface, for which a device with deforming rollers is installed, for example, in the tool holder of a lathe and a special elongated rotating center of the tailstock is passed through the central hole of the disk (not shown ) The blank of the screw is fixed in the spindle chuck of the front headstock and tighten the center of the tailstock. The workpiece of the screw being machined imparts a rotational motion V ₃ . 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.

A device with deforming rollers is informed of the longitudinal feed S _ol in one direction, which is determined by the formula:

S _ol = kS ₁ ,

where k is the number of deforming elements;

S ₁ - optimal feed per deforming element, is adopted for rollers no more - 0.01 ... 0.08 mm / rev.

During processing, the rocker arms leverage along the complex surface of the screw, providing constant guaranteed contact of the deforming rollers with the surface of the part. The levers perform a planetary motion, resting at one end on a fixed support - bearings. This allows you to process the workpiece with a longitudinal feed that is not equal to the pitch (for processing any screw surface by known methods, the longitudinal feed is equal to the pitch of the screw surface). Disks perceive axial forces arising during processing from levers, thereby locating deforming rollers normally to the axis of the workpiece.

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 rollers 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 machined composite surface. The ability to rationally use the energy of shock waves is determined by the size of the instrument.

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 process non-rigid screws (non-rigid parts such as shafts with a length to diameter ratio of more than ten are considered non-rigid [6]); 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.

Example. To assess the quality parameters of the surface layer hardened by the proposed method, experimental studies of the treatment of the screw of the left H41.1016.01.001 screw pump EVN5-25-1500 were carried out, which had the following dimensions: total length - 1282 mm, length of the screw part - 1208 mm, diameter the screw cross section is ⌀27 ^-0.05 mm, the eccentricity is 3.3 mm, the pitch is 28 ^{± 0.01} mm, the roughness R _a = 0.4 μm; single-helical screw surface, left direction; material - steel 18HGT GOST 4543-74, hardness HB 207-228, weight - 5.8 kg.

Processing by the proposed method was carried out on a screw-cutting machine mod. 16K20 using a device with a hydraulic hammer mod. DON UPI with Kar PTI with impact energy A = 250 J, maximum frequency f = 96 min ^-1 and efficiency = 0.47. The values of technological factors (impact frequency, tool roller radius, 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 tool pressed 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 the long-term action of large static forces [2-5]. 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. 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 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.

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.

A device that implements the proposed method is not complicated in design and reliable in operation, and the method of rolling in screw surfaces 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.

Processing according to 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. 02.

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 is a prototype.

4. RF patent No. 2275288, IPC B24 B 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.

6. 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 screws on machines, including communicating rotary motion to a workpiece, and a longitudinal feed motion rolling device, characterized in that a rolling device is used that contains two disks with central holes, one of which has an L-shaped holder for fixing the device to the machine support, and another 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 with united with each other by means of an axis mounted on 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 hydraulic hammer providing an impulse action on the free the end of the upper lever, the lower lever in the middle is supported on the outer ring of the bearing and the said hammer and load spring are fixed at its free end, while ensuring the creation of a permanent static load and an impulse load on the deforming elements.

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