RU2366558C1 - Method of flat surface hardening using rotor-type generator of mechanical pulses - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: rotation is imparted to deforming tool. Crosswise motion is imparted to workpiece. Deforming tool comprises central shaft and housing representing a disk with central bore and hollow shaft to transmit rotation from individual drive, peripheral bores to accommodate spring-loaded cams. Aforesaid central shaft support separator. The latter has peripheral bores to accommodate deforming tools representing step rod furnished with tape sprigs to produce static load. Static load pulse magnitude is adjusted by varying the cam offset from the housing and cam spring compression force.

EFFECT: expanded performances.

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Description

The invention relates to mechanical engineering technology, in particular to vibratory devices for finishing and hardening of steel and alloy parts by surface plastic deformation (PPD) with a static-pulse loaded deforming elements.

The known method and the device implementing it 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 and device are 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.

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

The method and device are 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, carried out using a mechanical pulse generator (GMI), for vibrational static-pulse hardening, characterized by independent regulation of energy and frequency of impacts [3, 4]. The GMI design includes: a waveguide with a deforming element mounted on it and a hammer, which are located in the housing, a static hydraulic cylinder on the housing, a hydraulic motor, a rotary valve spool, a pressure reducing valve and a throttle.

The known method carried out using GMI, is a very complex, expensive, metal and energy-intensive design, which significantly increases the cost of manufacturing the workpiece.

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 a rotary generator of mechanical impulses (RGMI) having cams and deforming elements running on them .

The problem is solved by the proposed method of static-pulsed vibration hardening of flat surfaces, carried out using a mechanical impulse generator, in which the deforming tool containing the casing and the separator with deforming elements is given rotational movement, and the workpiece is transversely moved, the casing being made in the form of a disk with a central a hole and a hollow shaft transmitting rotation from an individual drive, while in the peripheral holes of the casing installed springs cams with the possibility of regulating their departure in the longitudinal direction, and the separator is mounted on the central shaft, which is coaxially located in the hollow shaft, and has its own individual drive, while in the peripheral holes of the separator coaxial to the cams are installed deforming elements made in the form of stepped rods having Belleville springs to provide a static load, in addition, the pulse load is carried out due to the impact of the above cams on the deforming elements with a frequency, for isyaschey forced rotation speed of the hull and the speed of rotation of the separator, and the value of the pulse duty regulated emission of said cam body and the cam-compression springs.

Features of the proposed method are illustrated by drawings.

Figure 1 shows a diagram of the hardening of the flat surface of the workpiece by the proposed method using the developed RGMI, longitudinal section; figure 2 - General view of the Russian State Medical Institute; figure 3 is a section aa in figure 1; figure 4 - element B in figure 1, the contact zone of the cam with the deforming element, the shape of the working surface of the cam, flat with an angle of inclination a; figure 5 - element B in figure 1, the contact zone of the cam with the deforming element, the shape of the working surface of the cam, rounded with a radius R, convex; in Fig.6 - element B in Fig.1, the contact zone of the cam with the deforming element, the shape of the cam working surface, rounded with a radius R, concave; 7, 8, 9 - Belleville springs of different stiffness, providing a static load on the deforming elements and the clamping of the cams, design options, longitudinal section and end view.

The proposed method, implemented using a rotary generator of mechanical pulses (RGMI), is intended for static-pulse hardening of the flat surfaces of machine parts by surface plastic deformation. RGMI is installed, for example, on the headstock of a vertically milling machine (not shown), the housing 1 is informed of the rotational movement V _IR relative to its own longitudinal axis, the separator 2 is informed of the oncoming rotational motion V _ID and interference by means of longitudinal manual movement in the direction S _PR , and the workpiece 3, mounted on a table, - lateral feed S.

The developed design of the RGMI has a housing 1 made in the form of a disk with a central hole and a hollow shaft 4 transmitting the rotation of the V _IR from an individual drive (not shown). In the peripheral holes 5 of the housing 1, cams 7, spring-loaded by springs 6, are installed with the possibility of controlling their h outreach in the longitudinal direction. A set of Belleville springs 6 having different stiffness, due to the radial grooves (see Fig.7-9), you can set the required load on the cams 7. The force exerted by the springs 6 on the cams 7 is carried out by screws 8. In Fig.1-2 screwdrivers 8 are shown with a turnkey hexagon recess according to GOST 11738-72. The release of the cams 7 is limited by the cover 9, mounted on the end of the housing 1 with screws 10.

The separator 2 is rigidly fixed to the central shaft 11 with the help of a dowel and nut 12. The central shaft 11 is coaxially located in the hollow shaft 4 and has its own individual drive (not shown), which allows to develop the rotation speed V _ID both in the forward and counter directions relative to rotation of the hollow shaft 4. The central shaft 11 has a support consisting of rolling bearings 13 and the spacer sleeve 14.

In the peripheral stepped openings 15 of the separator 2 coaxially to the cams 7, deforming elements 16 are installed, made in the form of stepped rods. The deforming elements 16 are in one end contact with the cams 7 and the other with the processing surface 17 of the workpiece 3. To ensure the static load P _st exerted by the deforming elements on the surface to be treated, a packet of disk springs 18 is installed at a small stage of the deforming elements 16. At the ends of the separator 2 lids 19 and 20 are installed, which protect against the occurrence of deforming elements 16 and allow you to adjust P _Art . A set of Belleville springs 18 having different stiffness, due to the radial grooves (see Fig.7-9), you can set the necessary static load P _Art .

The impulse load P _{IM is} carried out due to the action of the cams 7 on the deforming elements 16 with a frequency depending on the speed of forced rotation of the housing V _IR and the speed of rotation of the separator V _ID , and the impulse load P _{IM is} provided and is regulated by the departure of the cams 7 from the housing 1 and the compression ratio cam springs 6.

Processing of the proposed method using the Russian State Medical Institute is as follows. The workpiece 3 is mounted on the table of the machine, for example, in a vice (not shown). RGMI is installed on the machine headstock (not shown). By moving S _{PR of the} machine headstock down the central shaft 11, the separator 2, through the cover 19, the springs 18 are statically pressed with the necessary force P _article deforming elements 16 to the hardened surface.

As a result of this action, plastic deformation of the surface of the workpiece by the value of α _st . In this case, the gap between the free end face of the deforming element and the cam surface must remain no more than h. The size of the gap can be provided with a probe whose thickness is not more than h and which is installed between the end face of the deforming element 16 and the cover 9 when the WGMI is pressed to the hardened surface and then removed before turning on the shaft rotation.

After the RGMI is static pressed to the hardened surface, the position of the RGMI is fixed and the feed S of the table with the workpiece is turned on, as a result of which the workpiece begins to move in the transverse direction relative to the deforming elements 16. The rotation of the V _IR hollow shaft 4 is turned on, which rotates the housing 1, while the cams will hit along the free ends of the deforming elements 16 with a force P _IM , pushing them into the hardened surface by the value of α _them . The magnitude and direction of the force P _IM depends on the shape of the cams, the size of their protrusion from the housing h, the stiffness of the cam springs 6, and the pulse frequency on the rotation speeds V _ik and V _id .

Cam springs 6 in the openings of the casing perform the function of damping elements, which reduce vibration loads on the entire structure of the Russian State Medical Institute and on the machine.

The kinetic energy of the impact will be affected by the angular velocity of the deforming elements 16 and the strength of their static compression to the hardened surface. The amount of impact energy transferred to the hardened surface will be determined by the shape of the shock pulses.

The method using RGMI allows loading of the hardened surface with shock pulses of various shapes.

The duration of the shock pulses is governed by the dimensions of the cross section of the deforming elements.

In contrast to the known hardening schemes, when the impact is carried out directly by the deforming element and the shape of the pulse is regulated only by changing the diameter and length of the deforming elements, the proposed method allows you to change the shape of the pulse due to the shape and size of the cams, which extends the technological capabilities and simplifies the design.

In contrast to the known methods and devices, it becomes possible to use not only a cylindrical, but also another shape for loading the deforming elements, for example, conical, hyperbolic, mountainous, etc., while the cams can be in the form of a cylinder or a prism with a flat end and with different values of the angle of inclination a of the end relative to the longitudinal axis of the cylinder (see figure 4); a rounded end with a different radius R, concave (see Fig.6) or convex (see Fig.5); shaped (mountainous, hyperbolic, etc.).

Example. Experimental processing was carried out — hardening by the proposed method using a flat surface RHMI with a width of 80 mm and a length of 590 mm on a vertically milling machine mod. 6P13; strengthened in one pass. The roughness parameter of the machined surface of the workpiece Ra = 3.2 microns. The roughness parameter of the machined surface of the finished part Ra = 0.32 μm. The workpiece material is steel 45 with a tensile strength σ _in = 670 MPa. The machine is equipped with a device for active control of workpieces. The treatment was carried out by the Russian State Medical Institute, in which the casing had an outer diameter of 130 mm, reinforcing, deforming elements were located at a diameter of 100 mm, the diameter of the deforming elements was 15 mm, and their number was 8 pcs. Processing was carried out in the following modes. The rotational speed of the casing with the cams and the separator was assumed to be multidirectional and equal to 50 min ^-1 , while the hardening speed was 31.4 m / min, table feed with the workpiece S = 250 mm / min. Coolant - emulsion. Deforming elements were made of an alloy of 38KhMYuA grade and after nitriding had a hardness of 60 ... 64 HRC. Then their working surface was polished to Ra = 0.04 ... 0.08 μm. With an axial impulse load of 400-600 N, the hardening of the surface layer reached 15 ... 25%. To ensure the required quality and dimensional accuracy of processing, the main time was 2.8 minutes, which is 2.4 times faster than with conventional hardening.

The depth of the hardened layer processed by the proposed method using RGMI 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 static-pulse processing, in comparison with traditional rolling, the effective depth of the layer, hardened by 20% or more, increases by 2 ... 3 times, and the depth of the layer hardened by 10% or more, by 1.7 ... 2.2 times.

The values of technological factors (impact frequency, amplitude value, feed value) 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 hardened layer during traditional static rolling is formed under long-term action of large static forces. The proposed method using RGMI similar 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 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 interfaced 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 1.1 ... 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 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 the instrument. The imposition of a small amplitude oscillatory motion leads to a more uniform distribution of the load on the tool, causes additional cyclic movements of the contact surfaces of the tool 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 advantage of the proposed method is the ability to create a specific orientation of the properties and texture of the surface layer of the metal, which improves the quality of processing; RGMI, with the help of which the method is implemented, is characterized by compactness and high efficiency, low energy intensity (compared with the known ones [2-4]), 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.

The proposed method extends the technological capabilities of static-pulse treatment by surface plastic deformation by controlling the depth of the hardened layer and the surface microrelief by using the RGMI, which generates a pulse load, and a tool of a special shape, and also improves the quality of processing.

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 - 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.

Claims (1)

The method of static-pulsed vibration hardening of flat surfaces, carried out using a mechanical pulse generator, comprising communicating rotational movement to a deforming tool comprising a casing and a separator with deforming elements, and transverse movement of the workpiece, characterized in that in the used deforming tool the casing is made in the form of a disk with central hole and hollow shaft transmitting rotation from an individual drive, and with peripheral holes for mounting cams with the possibility of regulating their departure in the longitudinal direction, and the separator is mounted on a central shaft coaxially located in the hollow shaft and having its own individual drive, the separator being made with peripheral holes in which said deforming elements are made coaxially with the cams, made in the form of stepped rods and having Belleville springs to provide a static load, while performing a pulsed load by the action of cams on deforming elements with frequent of the pulses depending on the speed of rotation of the body and forced the rotational speed of the separator, and the value of the pulse duty controlled emission of the cams of the housing and the degree of compression springs cams.

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