RU2383427C1 - Device for screw static-pulse strengthening - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: facility for fine-strengthening treatment is actuated for line feed, while billet is actuated to rotate around its own lengthwise axis. The facility for fine-strengthening treatment consists of a case wherein there are installed deforming elements and a wave guide made in form of a bushing, the facility also contains a nut and V-shaped bent leaf springs. The case is made with a central hole for billet positioning. The leaf springs with their end are rigidly secured on surface of the case hole, while on their other end there are arranged the said deforming elements; also cams are attached to their middle section. The cams contact internal surface of the wave guide whereto periodical pulse load is applied by means of a head; pulse load is generated with a hydraulic pulse generator. Cylinder compression springs are placed between the nut and a free end of the wave guide. Periodic pulse load is applied under condition of radial travel of the ends of leaf springs with deforming elements; notably, travel is directed to the centre of the billet.

EFFECT: expanded process functions, control over depth of strengthened layer and micro-relief of surface.

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Description

The invention relates to mechanical engineering technology, in particular to methods and devices for finishing and hardening processing of parts such as screws from steels and alloys by surface plastic deformation with static-pulse loading of deforming elements.

A known method and device for hardening processing, consisting of a vibrator of the reciprocal-longitudinal vibrations of the deforming element and the cam, driven into rotation from the electric motor through a stepless gearbox and designed to excite the transverse vibrational movements of this deforming element [1].

The method is characterized by limited control capabilities in creating heterogeneous hardened layers and regular microrelief of the treated surface, low efficiency, insufficiently deep hardened layer and insufficiently high degree of hardening of the treated surface.

A known method and device for shock vibratory rolling, comprising a housing, a separator with a deforming element, a support in the form of a smooth roller mounted rotatably in the housing, while it is equipped with a support drive and an elastic element, one end of which is mounted on the housing, and the other on the separator [2].

The known method is characterized by limited control capabilities in creating heterogeneous hardened layers and a regular microrelief of the treated surface, low efficiency, insufficient depth of the hardened layer and insufficiently high degree of hardening of the treated surface.

A device for static-pulse hardening of complex parts is also known, containing a chamber that is filled with deforming elements in the form of microspheres or balls and is configured to place a workpiece in it, and a waveguide, while it is equipped with two pads placed in the chamber with concave cylindrical surfaces, a striker , the first hydraulic cylinder connected to the hydraulic pulse generator to create a pulse load on the deforming elements, and the second hydraulic cylinder, made with possible the impact on the first hydraulic cylinder to create a static load on the deforming elements, the latter are located between the cylindrical concave surfaces of the blocks and the workpiece with the possibility of covering the latter, one of these blocks is made with the possibility of movement and pivotally connected to the waveguide, the camera is made with through holes in its two opposite the walls to ensure the passage of the workpiece and contains gates with shock absorbers located in the said through holes of the chambers s, while the waveguide and the firing pin are made of the same diameter and are located in the first hydraulic cylinder [3, 4].

The known method and device that implements it, which is a very complex, expensive, metal and energy-intensive design, which significantly increases the cost of manufacturing the workpieces, the method is characterized by limited control capabilities in creating heterogeneous hardened layers and regular microrelief of the treated surface.

The objective of the invention is to expand the technological capabilities of static-pulse treatment by surface plastic deformation by controlling the depth of the hardened layer, the degree of hardening and the surface microrelief, with minimal energy consumption and the complexity of manufacturing equipment by using deforming elements suspended on elastic plates interacting with the waveguide and the striker.

The problem is solved by the proposed method of static-pulse hardening of screws, including a message of the longitudinal feed to the device for finishing and hardening processing and rotational movement relative to its own longitudinal axis of the workpiece, characterized in that they use a device for finishing and hardening processing, comprising a housing with a central hole for positioning in blanks in which the deforming elements and the waveguide, made in the form of a sleeve, a nut and a V-shaped curved plate springs, with one end rigidly fixed to the surface of the housing opening, at the other end of which the aforementioned deforming elements are installed, and cams are fixed on their middle part, which contact the inner surface of the waveguide, to which, using the striker, apply a periodic pulse load generated by a hydraulic pulse generator, in this case, cylindrical compression coil springs are installed between the nut and the free end of the waveguide to return the waveguide to its original position, but not iodicheskuyu impulse load is applied from the condition of creating a radial movement directed to the center of the workpiece ends with leaf springs deforming elements, straightening them and create interference.

Features of the proposed method are illustrated by drawings. Figure 1 shows a diagram of the hardening of the helical surface of a screw blank on a lathe using a three-jaw self-centering chuck with preloading by the rear center and a device that implements a method that is shown in working position at the time of the action of the pulse load, a longitudinal section; figure 2 - the device at idle, when the deforming elements are removed from the surface of the workpiece, a partial longitudinal section; figure 3 is a view a in figure 1, a General view of the device from the end; figure 4 is a cross section bB in figure 1; figure 5 - element In figure 1, the position of the deforming element during the action of the pulse load and idle (thin line); in Fig.6 - element G in Fig.2, the deforming element is fixed in the separator, the position of the deforming element during idle.

The proposed method is intended for static-pulse hardening of screws by surface plastic deformation (PPD). The method is implemented using a device that is installed, for example, on a support of a lathe (not shown), and the screw blank 1, mounted in a three-jaw self-centering chuck 2 and preloaded by the rear center, is provided with a rotational movement V _З relative to its own longitudinal axis, and the device is longitudinal supply S _PR , while the deforming elements 3 - static P _ST and pulsed P _IM radial loads directed to the center of the workpiece S _P.

The proposed method is implemented by a device having a housing 4, which is part of the hydraulic cylinder and covers the workpiece 1. The hydraulic cylinder is made in the form of two concentric cylinders: external and internal, where the waveguide 5 and the strikers 6 are made in the form of bushings.

On the inner surface of the inner cylinder, V-curved leaf springs 7 are rigidly fixed at one end. Leaf springs 7 are made, for example, of cold-rolled steel tape according to GOST 21996-76. At the other free end of the leaf springs 7, deforming elements 3 are installed. The deforming elements 3 can be fixed to the leaf springs 7 both rigidly and movably using a separator. An option for mounting deforming elements 3 on leaf springs 7 using a separator 8 is shown in Fig.6. On the middle part of the leaf springs 7, cams 9 are fixed, which are in contact with the inner surface of the waveguide 6, which is at an angle to the longitudinal axis, so that during reciprocal longitudinal movement of the waveguide, the cams and the free end of the leaf springs with deforming elements will move radially direction S _P.

The waveguide 6 is a sleeve and is placed between the outer and inner cylinders of the housing 4. The periodic impulse P _IM load of the waveguide 6, directed longitudinally, is converted to an additional message of radial movement of the free ends of the leaf springs 7 with deforming elements 3. When the striker 5 hits the waveguide 6, the last extends from the housing 4 and, in contact with the cams 9, radially moves to the center the free ends of the springs 7 with deforming elements 3, straightening the springs and making a blow to the reinforced surface Workpiece 1.

To return the waveguide 6 to its original position, namely, moving to the housing 4, cylindrical compression coil springs 10 are used, installed between the nut 11, which is screwed onto the outer cylinder of the housing 4, and the free end of the waveguide 5.

The method can be implemented in static mode, when the hydraulic pulse generator (not shown) is turned off and does not generate a pulse load, while the hammer 5 does not work, and the waveguide 6 is installed in the leftmost position (according to figure 1), while the deforming elements 3 have the maximum static P _ST ^MAX impact on the surface 1. When installing the waveguide 6 in an intermediate position between the leftmost (figure 1) and right (figure 2) positions, you can load the deforming elements of any static P _ST load viscous within P _PT ^MAX > P _CT > 0.

The proposed method is most effectively applied in a pulsed mode, when a hydraulic pulse generator (not shown) is turned on and generates a pulsed P _MI load, the striker 5 operates and acts on the waveguide 6 (according to FIG. 1) in the longitudinal direction, while the deforming elements 3 perceive pulse R _IM load, move in the transverse radial direction and have a strengthening effect on the treated surface 1.

If the waveguide 6 does not reach the extreme right position, i.e. to the position, as when idling (figure 2), the device will work in a static-pulse mode.

The frequency of the pulsed action of deforming elements on the surface to be treated depends on the frequency of the strikes on the waveguide.

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 on a leaf spring with a deforming element and on the surface to be treated with a cyclicity equal to double pulse duration. Having reached the surface to be treated, the shock pulse is distributed on the passing and reflecting. The passing pulse forms a dynamic component of the hardening force, which intensifies the process.

The ability to rationally use the energy of shock waves is determined by the dimensions of the device experimentally.

The total longitudinal periodic pulsed load P _{IM of the} striker along the waveguide is perceived by leaf springs and evenly distributed to each deforming element.

The periodic impulse load P _IM must be greater than the total force required to deform the cantilever part of the leaf springs to overcome the resistance of the coil springs 10 and the force necessary for hardening. The removal of the waveguide and the striker after impact in the initial position (according to Fig.1-2, to the right) is due to the elasticity of the cylindrical coil springs 10 and the return of the bent part of the leaf springs to their original free state.

The pulse mode of the RPM, characterized by the presence of an impact load P _IM , is carried out due to the impact of the striker on the waveguide and then the latter acts on the cams of leaf springs with deforming elements with a frequency depending on the frequency of the hydraulic pulse generator [5-7], which supplies the hydraulic cylinder of the housing 4.

The magnitude of the impulse load P _{IM is} ensured by the stiffness of the leaf springs and the magnitude of their deflection, which depends on the design parameters of the cams 9. When the waveguide hits the cams, the leaf springs bend, and the deforming elements hit the force P _IM on the hardened surface, pressing into it by the value of α _them .

The accuracy of the shape of the workpiece’s machined surface with this device is increased, and the roughness is reduced due to self-centering and self-installation of deforming elements on the machined surface during its beating and vibration. The device, covering the workpiece over the entire diameter in cross section, supports the workpiece as a rest.

The leaf springs, on which the deforming elements are installed, additionally perform the function of damping elements, which reduce vibration loads on the entire structure of the device and on the machine.

Example. To assess the quality parameters of the surface layer hardened by the proposed method, experimental studies of screw processing using a hydraulic pulse generator were carried out [5-7]. The screw left H41.1016.01.001 of the screw pump EVN5-25-1500 was processed on a lathe using the device described above. The screw (see Fig. 1) had the following dimensions: total length - 1282 mm, screw part length - 1208 mm, screw cross-sectional diameter ⌀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 this device.

The values of technological factors (impact frequency, longitudinal feed rate, workpiece rotation speed, etc.) 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 forces of static and pulsed loads of deforming elements on the treated surface was P _article = 25 ... 40 kN; P _them = 255 ... 400 kN. The depth of the hardened by static-pulsed processing layer is 3 ... 4 times higher than with traditional rolling. The hardened layer in the traditional static rolling 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 by the proposed method is much smaller.

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 1.1 ... 1.3 times greater than the depth of the riveted layer, which is consistent with the theory of PPD.

The ultimate roughness value achieved during processing by the proposed method is R _a = 0.08 μm, a reduction of the initial roughness by a factor of 5 is possible.

Microvibrations in the process favorably affect the working conditions of deforming elements. 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 elements periodically "rests", which contributes to an increase in 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 deforming elements and the workpiece.

The proposed method extends the technological capabilities of static-pulse processing of screws by surface plastic deformation, allows you to control the depth of the hardened layer and the surface microrelief.

The advantages of the proposed method are the ability to create a certain orientation of the properties and texture of the surface layer of the metal, which improves the quality of processing; a device that implements the method is characterized by compactness and high efficiency, low energy intensity (compared with the known [5-7]), a sufficiently large depth of the hardened layer and a sufficiently high degree of hardening of the treated surface; The method has wide control capabilities in creating heterogeneous hardened layers and regular microrelief of the treated surface.

Information sources

1. A.S. USSR 366062, IPC V24V 39/00. The method of hardening the surface of metal parts. G.M. Azarevich. 1616331 / 25-8. 12/07/1970; 01/10/1973.

2. A.S. USSR 1238952, IPC V24V 39/00. Device for shock vibratory rolling. Yu.G. Schneider, B.N. Bukin, G.R. Kruglov. 3818752 / 25-27. 12/04/1984; 06/23/1986.

3. RF patent 2319596. IPC V24V 39/04. Device for static-pulse hardening of complex parts. Stepanov Yu.S., Kirichek A.V., Afanasyev B.I., Samoilov N.N., Fomin D.S., Mikhailov G.A., Inozharsky V.V., Gavrilin A.M., Selemenev K.F. Application No. 2006125126/02. 07/12/06. 03/20/2008. Bull. No. 8.

4. RF patent 2319597. IPC V24V 39/04. The method of static-pulse hardening of complex parts. Stepanov Yu.S., Kirichek A.V., Afanasyev B.I., Samoilov N.N., Fomin D.S., Mikhailov G.A., Inozharsky V.V., Gavrilin A.M., Selemenev K.F. Application No. 2006125135/02. 07/12/06; 03/20/2008. Bull. No. 8.

5. RF patent 2098259, MKI ⁶ V24V 39/00. Lazutkin A.G., Kirichek A.V., Soloviev D.L. The method of static-pulse treatment by surface plastic deformation. 96110476/02, 05.23.96; 12/10/97. Bull. Number 34.

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

7. 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)

The method of static-pulse hardening of screws, including the message of the longitudinal feed to the device for finishing and hardening processing and rotational movement relative to its own longitudinal axis of the workpiece, characterized in that they use a device for finishing and hardening processing, comprising a housing with a central hole for positioning the workpiece in it, which are the deforming elements and the waveguide, made in the form of a sleeve, a nut and a V-shaped curved leaf springs, one end rigidly fixed to the surface of the housing opening, at the other end of which the aforementioned deforming elements are installed, and on their middle part cams are fixed that contact the inner surface of the waveguide, to which, using the striker, apply a periodic impulse load generated by a hydraulic pulse generator, between the nut and the free end waveguide compression coil springs are installed to return the waveguide to its original position, and a periodic pulse load is applied from the condition of creating a radial movement directed to the center of the workpiece, ends of leaf springs with deforming elements, straightening them and creating an interference fit.

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