RU2364490C1 - Method of flat surface static-and-impulse strengthening - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to metalworking and is to be utilised for strengthening treatment of flat surfaces of items by way of surfacial plastic deformation. One provides for transmission of a rotary motion to the deformation tool containing a body with deformation elements. One provides for transmission of a crosswise motion to the blank. The deformation tool body consists of a cammed plate and an upper and a lower separators containing deformation elements moveably installed so that to be capable of longitudinal motion. The deformation elements are represented by differential rods whereupon springs are attached between the said separators providing for static load regulation. One provides for generation of impulse load due to the said cams impacting the deformation elements with a frequency depending on the plate forced rotation speed with the impulse load intensity regulated via the cams projection outside the plate.

EFFECT: extension of technological capabilities combined with processing quality improvement.

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Description

The invention relates to metal working and can be used in the hardening treatment of flat surfaces of parts by surface plastic deformation (PPD).

A known method of hardening flat surfaces, implemented by a device consisting of a housing and heads eccentrically mounted in it, on the treadmills of which deforming elements are placed, while, in order to improve the quality of processing, curved grooves are made in the housing designed to be installed in them with the possibility of movement and fixing said heads, the axes of which are located at different distances from the axis of the housing [1].

The disadvantage of this method is the impossibility of creating a certain orientation of the properties and texture of the surface layer of the metal, which reduces the quality of processing, while the method is characterized by low efficiency, high energy consumption, insufficient depth of the hardened layer and insufficiently high degree of hardening of the processed surface, in addition, the method has limited capabilities control 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 processing by surface plastic deformation by controlling the depth of the hardened layer and the surface microrelief by using a device that generates a pulse load and a tool of a special shape, as well as improving the quality of processing.

The problem is solved by the proposed method of static-pulse hardening of flat surfaces, in which the deforming tool containing the casing with deforming elements is informed of rotational movement, and the workpiece is transversely moved, the casing being made of a plate with cams, upper and lower separators, the latter are movable with the possibility of longitudinal movement installed deforming elements made in the form of two-stage rods on which between the above separators is located There are springs that provide the possibility of regulating the static load, while the impulse load is carried out due to the influence of the said cams on the deforming elements with a frequency depending on the speed of the forced rotation of the plate, and the magnitude of the impulse load is controlled by the departure of the said cams from the plate.

The processing features of the proposed method are illustrated by drawings.

Figure 1 shows a device that implements the proposed method, a longitudinal section, and a diagram of hardening the flat surface of the workpiece; figure 2 - General view of the device; figure 3 is a section aa in figure 1; figure 4 - diagram of the work in the static hardening mode, the deforming element is not affected by the pulse load; figure 5 - diagram of the work at the time of the beginning of the touch of the cam deforming element; figure 6 - scheme of operation in the mode of static-pulse hardening, at the time of the transverse force, rotating the separators with deforming elements relative to the longitudinal axis; 7 is a diagram of the operation in the mode of static-pulse hardening at the time of the maximum pulse P _them load.

The proposed method is intended for static-pulse hardening of the flat surfaces of machine parts by surface plastic deformation. The method is implemented by a device installed, for example, in the spindle of a vertically milling machine (not shown), which is informed of a rotational movement of V _And relative to its own longitudinal axis and interference by means of longitudinal manual movement S _pr , and the workpiece is transverse feed S.

The device has a prefabricated housing consisting of a plate 1, upper 2 and lower 3 separators, and deforming elements 4 (according to Fig.1-2).

In the upper 2 and lower 3 separators, made in the form of disks, along the sliding fit in the peripheral holes are installed deforming elements 4, which are made in the form of two-stage rods, and with a step of a smaller diameter, the rods are installed in the upper separator 2. Between the separators 2 and 3 on the deforming elements 4, coil cylindrical compression springs 5 are installed that create a static load P _{st of the} reinforcing effect of deforming elements on the surface to be treated. The top end of the spring 5 abuts against the end of the upper separator 2, and the bottom end of the step of the larger diameter of the deforming elements 4. By approaching or removing the separators from each other, the static load force P _{st is} controlled by screws 6 and interchangeable spacer sleeves 7.

The upper and lower separators 2 and 3 through their central holes, in which the bushings 8 are pressed, which play the role of sliding bearings, are axially connected to the plate 1 of the device using the axis 9 movably with the possibility of rotation relative to the central longitudinal axis. Axis 9 is rigidly secured to the central longitudinal axis of the plate 1, and is available on the axis 9 stage 10 serves the bigger-diameter focusing transmitting longitudinal movement of the hand from the _straight shank S 11 and separator plates 1 2 and 3.

Cams 12 are located in the plate 1, in this device design they are presented in the form of balls. The plate 1 has cylindrical blind holes, in each of which a spring 13, a washer 14, and a cam 12 are sequentially mounted, which are held by a cover 15 with holes fixed by screws 16 to the plate 1. The spring 13 abuts against the bottom of the hole of the plate 1 on one side and on the other, through the washer 14, into the cam 12, which protrudes from the opening of the cover 15 by a value of h. A cone 11 is attached to the plate 1 from above by bolts 17, with the help of which it is mounted in the machine spindle.

In order to compensate for the installation error of the device relative to the workpiece surface, a centering ball 18 is installed between the cone 11 and the plate 1, and the bolts 17 are in contact with the surface of the cone flange 11 through the rubber bushings 19.

Work on the proposed method is as follows. The workpiece 20 is mounted on the table of the machine, for example, in a vice (not shown). The device cone 11 is inserted into the spindle of the machine (not shown). By moving S _{pr the} machine spindle down the cone 11, the plate 1 by the protrusion 10 of the axis 9 is pressed against the upper separator 2, which through the springs 5 statically compresses the deforming elements 4 to the hardened surface with the necessary force P _st .

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 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 4 and the cam when the device is pressed to the hardened surface and then removed before turning on the spindle of the machine.

After the static device is drawn to the hardened surface, the spindle position 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 4. The rotation of V _{and the} spindle, which rotates the plate 1, starts, while the cams will hit free the ends of the deformation elements 4, and develop the strength F (5-6) while shifting them in the tool rotational direction with a force F _dd some distance L and pushing in the reinforcing behavior ited to force _them on the value of P and _them. The magnitude and direction of the force P depends on the shape of the cams, the size of their protrusion from the plate h, the stiffness of the cam springs 13, and the pulse frequency on the rotation speed V _and .

Cam springs 13 in the holes of the plate perform the function of damping elements that reduce vibration loads on the entire structure of the device and on the machine.

The kinetic energy of the impact will be affected by the angular velocity of the deforming elements 4 and the strength of their static drawn 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 device allows loading 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 pulse shape is controlled only by changing the diameter and length of the deforming elements, in this device the pulse shape can be changed due to the shape and size of the cams, which extends the technological capabilities and simplifies the design.

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

Example. Experimental processing was performed — hardening by the proposed method of a flat surface 80 mm wide and 590 mm long 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 processing was carried out by a device in which the plate 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 plate with the cams was taken to be 50 min ^-1 , while the hardening speed was V _and = 15.7 m / min, the feed of the table with the workpiece was 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 necessary quality and dimensional accuracy of processing, the main time was 2.4 minutes, which is 2.5 times faster than with conventional hardening. 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 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, 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 minting, 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 1.1 ... 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 the processing of the proposed method is Ra = 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 advantages of the proposed method is 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 compact and has high efficiency, low energy consumption (compared with the known ones [2, 3]), 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 a device that generates a pulse load and a tool of a special shape, and also improves the quality of processing.

Information sources

1. USSR author's certificate No. 944897, V24V 39/00. Device for hardening flat surfaces. Vishnev N.V. and other Application No. 2977796 / 25-08; 09/03/1980; 07/23/1982. Bull. No. 27 is a prototype.

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

3. 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 method of static-pulse hardening of flat surfaces, comprising communicating rotational motion to a deforming tool comprising a housing with deforming elements and transverse movement of the workpiece, characterized in that the housing is made in the form of a plate with cams and upper and lower separators, in which it is movable with the possibility of longitudinal movement deforming elements are installed, made in the form of two-stage rods on which springs are located between the said separators, providing with zmozhnostyu adjusting a static load, thus creating an impulse load said cams influence on the deformation elements with a frequency dependent on speed of rotation force plate, and the magnitude of the pulse duty is controlled by the departure of the cam plate.

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