RU2350456C1 - Device for pulse strengthening of screws - Google Patents

Abstract

FIELD: technological processes; tool.

SUBSTANCE: device comprises body with deforming elements installed in it, striker and wave guide arranged with the possibility of periodical pulse load application. Deforming elements are arranged in the form of disk springs having solid flat peripheral end surface, and in central part - conic surface with radial slots and interrupted central hole. Disk springs are coaxially mounted in rings with the help of damper and are assembled in packet with spacer rings and with location of their radial slots in staggered order relative to each other. Specified packet of disk springs is installed between internal collar of nut fixed on the body and wave guide.

EFFECT: technological resources are expanded, efficiency is increased, and prime cost is reduced.

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Description

The invention relates to mechanical engineering technology, in particular to methods and devices for finishing and hardening the treatment of surfaces of parts of shafts or screws of steels and alloys by surface plastic deformation (PPD) with impulse loading of a deforming tool.

Known hardening head with an elastic tool, which contains a housing with flanges located on its ends, and deforming elements in the form of turns of a coil spring installed in the housing and made of steel wire of circular cross section, and the spring is folded along a helix with the possibility of setting the workpiece and rigidly fixed by the ends in the flanges, made with the possibility of rotation and fixation in the circumferential position to ensure the impact on the workpiece of the coil of spring billet nuts [1].

The known method and device is characterized by limited control capabilities in creating heterogeneous hardened layers and regular microrelief of the treated surface, design complexity and low productivity, and also requires very great efforts for efficient processing.

The objective of the invention is to expand the technological capabilities of pulsed processing by surface plastic deformation by controlling the depth of the hardened layer and the microrelief of the screw surface of the screws by using a device and a special tool with a large number of deforming elements that are affected by periodic pulsed load, which allows to increase productivity and reduce costs manufacturing due to simplicity of design.

The problem is solved using the proposed device for pulsed hardening of shafts or screws of screw pumps, which contains a housing with deforming elements located therein, a striker and a waveguide, to which a periodic pulsed load generated by a hydraulic pulse generator (GGI) is applied, and the deforming elements are made in the shape of Belleville springs having a continuous flat peripheral end surface, and in the central part a conical surface with an inclination angle α to the prices the swivel axis and radial grooves, as well as a discontinuous central hole in which the workpiece of the screw being machined is located, and the Belleville springs are coaxially mounted in rings with a damper and stacked in a bag with spacer rings and radial grooves staggered relative to each other and convex conical end faces to each other, and the said package is installed between the inner flange of the nut, which is mounted on the housing, and the waveguide, made in the form of a sleeve, in addition, in the form of a sleeve a striker is made, since the casing is two coaxial cylinders, in the central hole of which a workpiece is located.

The essence of the design of the device is illustrated by drawings.

Figure 1 presents the processing scheme of the proposed device for pulse hardening of screw surfaces of screws, a partial longitudinal section, disk springs in a free, unloaded state; figure 2 is the same, Belleville springs in a loaded state; figure 3 - the same combined longitudinal section, cup springs in a free unloaded (above the longitudinal axis) and loaded (below the longitudinal axis) state; figure 4 is a cross section aa in figure 1; figure 5 is a diagram for calculating the angle of inclination of the conical part of the Belleville spring; figure 6 - element In figure 4.

The proposed device is intended for surface plastic deformation (PPD) hardening of shafts or screw surfaces of the screws of screw pumps using periodic pulsed loads on deforming elements.

The proposed device comprises a housing 1, which is two coaxial cylinders: the outer 2 and the inner 3, through the Central hole of the latter pass the workpiece 4. From one end of the housing 1 (for example, on the left according to figure 1) in the outer cylinder 2 are located: waveguide 5, made in the form of a two-stage sleeve, and the hammer 6 in the form of a single-stage sleeve. Generated by the GGI (not shown) periodic pulses are transmitted to the hydraulic cylinder 2 and are sensed by the striker 6, which transmits them to the waveguide 5 in the form of a periodic pulsed load P _IM [2-6].

The deforming elements 7 located in the housing 1 are made in the form of disk springs and have a continuous flat peripheral end surface, and in the central part there is a conical surface with an angle of inclination α to the transverse plane perpendicular to the central longitudinal axis. The Central conical part of the Belleville spring 7 is made with radial grooves, due to which the petals 7 _{L are formed} , cantileverly mounted on the peripheral flat part of the Belleville spring. As a result of this design of the disk spring, the inner surface of its hole in contact with the workpiece is discontinuous.

The Belleville spring 7 is coaxially mounted in the ring 8 using a damper 9. The damper 9 is made of rubber, which, by vulcanization, connects the spring 7 to the ring 8.

The ring 8 is rigidly fixed in the housing of the device, while the cup spring 7 has the ability to move in space in both axial and radial directions. These movements of the spring 7, due to the damper 9, are necessary for its self-installation on the machined screw surface of the screws of the screw pumps, which, as a rule, is performed with an eccentricity "e".

An even number of springs 7, but not less than two, are stacked with spacer rings 10 and radial grooves staggered relative to each other and with convex conical ends to each other. A package of springs 7 is installed between the inner end flange of the nut 11, which is mounted on the housing 1, and the waveguide 5, while the latter is in contact with a continuous flat peripheral end surface of the disk spring. The firing pin 6 senses the oil pressure drops - pulses generated by the GGI and entering the hydraulic cylinders 2 and 3, and transmits a periodic impulse load P _IM in the form of an impact on the waveguide 5. When moving the waveguide 5 from right to left, according to figures 1-3, cup springs 7 perceive the periodic impulse load Rome, due to which they move to the inner end flange of the nut 11 and their conical parts bend, approaching the transverse plane passing through the end flat peripheral part of the disk plate dinners. The angle of inclination α of the petals of the conical part and the diameter of the hole of the Belleville spring are reduced (see figure 5).

The sharp edges of the deforming elements of the springs - petals 7 _L , which are in direct contact with the workpiece surface 4, are made rounded with a radius R = H / 2, where H is the thickness of the Belleville springs, mm.

The total longitudinal periodic pulsed load P _{IM of the} waveguide is perceived by the whole package of Belleville springs and is evenly distributed to each spring. This means that each Belleville spring 7 has a reinforcing effect with a pulse load P _IM ^N directed along the normal to the surface to be treated.

The nominal internal diameter of the hole d _{T of the} Belleville spring is: d _T = d _Z + 2z mm,

where d _T is the inner diameter of the disk spring hole in a free, unloaded state, mm;

-uprochnyaemy diameter d _of the workpiece, mm;

z - guaranteed clearance required for free entry of the workpiece screw into the device, mm; The following guaranteed clearance values are recommended: 20 <d _z <30 z = 0.1; 30 <d _s <50 z = 0,2; 50 <d _s <80 z = 0.3; 80 <d _z z = 0.4.

The angle of inclination α of the conical part of the Belleville spring depends on the length of the petal y, the guaranteed clearance z and the interference value h and must be at least: α> arc cos (1-z / y-h / y), deg.

where a is the angle of inclination of the conical part of the Belleville spring, mm;

y is the length of the generatrix of the cone of the Belleville spring, i.e. petal length, mm;

h is the tightness necessary for hardening, mm

However, the deforming elements of the spring do not reach the minimum diameter d _T ^min , due to the fact that the latter is less than the diameter of the workpiece d ₃ , due to this, an interference fit h is created, while all deforming elements — petals 7 _{L of the} spring — are in contact with the treated helical surface and surface hardening is realized blanks.

A hydraulic pulse generator [4, 5] or other known design (not shown) is used as a mechanism for pulse loading of Belleville springs.

Belleville springs 7 can be made according to GOST 3057-79 from steel 60C2A (or other spring steel according to GOST 14963-78) with different sizes of deforming elements in contact with the workpiece. The more radial grooves a Belleville spring has, the less its rigidity and resistance to deflection and the smaller the contact area of the deforming elements with the work surface.

When processing the workpiece receives a rotation V _s , and the device for hardening - the movement of the longitudinal feed S _CR along the axis of the workpiece. During input of the device into the hole to be processed, the deforming disk springs 7 are in a free state and their inner diameter is larger than the outer diameter of the screw being machined; the number of Belleville springs 7 in the package must be even, at least two and depends on the specific processing conditions and technical requirements for the surface to be treated, it is established experimentally taking into account design features.

A periodic pulsed P _IM load is applied in the direction of the longitudinal feed and, thanks to the design features of the deforming elements - Belleville springs, direct it along the normal to the work surface.

The periodic impulse load of Rome must be greater than the total force required for the deformation of the Belleville springs and the force necessary for hardening. The removal of the waveguide and the striker after impact in the initial position (according to Fig.1-3 to the right) is due to the elasticity of the Belleville springs and return them to their original free state. The shock absorber 12, mounted on the end of the cylinder 3, is designed to mitigate the impact when the waveguide is retracted to its original position.

As a result of the impact of the striker 6 on the waveguide 5 and the last on the end of the packet of Belleville springs, the deforming elements act on the surface to be treated with the cyclicity set by the hydraulic pulse generator. The ability to rationally use the energy of shock waves is determined by the size of the deforming springs.

The device is intended for pulse hardening by surface plastic deformation of parts such as shafts or screws of screw pumps, for which the device is installed, for example, on a support of a lathe and a special elongated rotating center of the tailstock (not shown) is passed through the central hole. The workpiece of the shaft or screw is fixed in the chuck 13 of the spindle 14 of the front headstock 15 and is pressed by the center 16 of the back headstock 17. The workpiece of the processed shaft or screw is informed of a rotational movement V _s . 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 _ol in one direction.

The depth of the hardened layer treated by the proposed method reaches 1.5 ... 2.5 mm, which is significantly (3 ... 4 times) more than with traditional static hardening. The greatest degree of hardening is 15 ... 30%. As a result of pulsed processing compared to traditional rolling, the effective depth of the layer hardened by 20% or more increases by 1.8 ... 2.7 times, and the depth of the layer hardened by 10% or more by 1.7 ... 2, 2 times.

Example. To assess the quality parameters of the surface layer hardened by the proposed device, 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, transverse diameter screw sections - ⌀27 ^-0.05 mm, eccentricity - 3.3 mm, pitch - 28 ^{± 0.01} mm, 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 was carried out on a mod screw-cutting machine. 16K20 using the proposed device equipped with a hydraulic pulse generator.

The values of technological factors (impact frequency, feed rate) were chosen in such a way as to ensure the 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 strength of the static and pulsed preload of the deforming elements to the treated surface was P _article > 25 ... 40 kN; P _MI = 255 ... 400 kN. The depth of the layer hardened by pulsed processing is 3 ... 4 times higher than with traditional rolling. The processing of the proposed device can improve productivity by 1.5 ... 2.0 times and ensure high accuracy.

The hardened layer in the traditional static rolling is formed under long-term action of large static forces. The proposed device the same depth of the hardened layer is achieved as a result of short-term exposure to 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 of the proposed device is much less.

Studies of the stress state of the hardened surface layer by pulsed processing 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 1.1 ... 1.3 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 is R _a = 0.08 μm; a possible initial roughness decrease by 4 times is possible.

Microvibrations during processing favorably affect the working conditions of Belleville springs. The imposition of a small amplitude oscillatory motion leads to a more uniform distribution of the load on the deforming elements, causes additional cyclic movements of the contact surfaces of the deforming elements and the workpiece, facilitates the formation of a hardened surface. Fluctuations contribute to a better penetration of the cutting fluid (coolant) into the treatment area. When vibration is applied, the deforming surface of the tool periodically “rests”, which helps to increase its resistance. Processing under vibration conditions dramatically increases the efficiency of the cooling, dispersing and plasticizing action of the coolant due to the facilitation of its access to the contact zone of the tool and the workpiece.

The proposed device extends the technological capabilities of pulsed processing by surface plastic deformation by controlling the depth of the hardened layer and the microrelief of the inner surface by using a device and a special tool with a large number of deforming elements, which allows to increase productivity and reduce manufacturing costs.

Information sources

1. RF patent 2303515, MKI V24V 39/04. Stepanov Yu.S., Kirichek A.V., Afanasyev B.I. and others. Reinforcing head with an elastic tool. No. 2005137070/02, 07/05/2005; 09/20/2006. Bull. No. 26 is a prototype.

2. RF patent 2283748, MKI V24V 39/02. Stepanov Yu.S., Kirichek A.V., Soloviev D.L., Afanasyev B.I., Fomin D.S., Afonin A.N., Samoilov N.N. Device for static-pulse rolling. No. 2005121091/02, 07/05/2005; 09/20/2006. Bull. No. 26.

3. A.S. USSR, 456719, MKI V24V 39/00. The method of finishing and hardening of parts by rolling. 1974.

4. RF patent 2098259, MKI ⁶ V24V 39/00. Lazutkin A.G., Kirichek A.V., Soloviev D.L. Method of static pulse treatment by surface plastic deformation. No. 96110476/02, 05.23.96; 12/10/97. Bull. Number 34.

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

6. 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.

Claims (1)

A device for pulse hardening of shafts or screws of screw pumps, comprising a housing with deforming elements located therein, a striker and a waveguide configured to apply a periodic impulse load generated by a hydraulic pulse generator, characterized in that the deforming elements are made in the form of disk springs having a continuous a flat peripheral end surface, and in the central part a conical surface with an angle of inclination to the central axis, with radial grooves and an intermittent central hole in which the workpiece is located, and the Belleville springs are coaxially mounted in rings with a damper and stacked in a bag with spacer rings and with the arrangement of their radial grooves in a checkerboard pattern relative to each other and convex conical ends to each other, and the said package Belleville springs are installed between the inner flange of the nut, which is mounted on the body, and the waveguide, while the waveguide and the striker are made in the form of bushings, the body is made in the form of two coax lnyh cylinder to be positioned in the central opening of the preform.

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