RU2355554C1 - Deforming tool for hole pulse strengthening - Google Patents

Abstract

FIELD: engineering industry.

SUBSTANCE: invention refers to engineering industry technology, namely to methods of finishing - strengthening treatment of parts holes by surface plastic deformation. Deforming instrument contains united in a pack washer plates, rod on which there are washer plates with the possibility of their lateral movement and changing of cone angle of their end surface and pane. Washer plates are performed with front conic surface, radial channels and central hole. Washer plates are performed with the possibility of pulse load perception from the pane, sagging by f value, increase of their diametre and provision of pulse load direction along normal line towards treated surface. Sagging f value of plate washers is defined by mathematical expression.

EFFECT: extension of technological capabilities, increase of production rate and decrease of expenses.

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Description

The invention relates to mechanical engineering technology, in particular to finishing and hardening processing of holes of parts from steels and alloys by surface plastic deformation with a pulse loaded tool.

Known deforming tool for pulse hardening of holes, containing single deforming elements (the surface of the disk springs in contact with the work surface) located on the radial pushers in the form of disk springs made with radial recesses - recesses, and the strikers in the form of a rod (5 for transmission impulse loads of Belleville springs, while Belleville springs are cantilevered at an acute angle to the longitudinal axis of the deforming tool, have a Central hole for For installation on a mandrel, they are assembled in a package and installed with the possibility of longitudinal movement and change of the aforementioned angle of their inclination when the rod-striker moves in the axial direction, disk springs are made with the possibility of absorbing the longitudinal periodic impulse load of the rod-striker of deflection, increasing the diameter and direction pulse load at the time of their compression along the normal to the surface being machined [1].

The known deforming tool is characterized by limited control capabilities in creating hardened layers and regular microrelief of the machined surface, as well as the complexity of the design and low productivity.

A known method and device for static-pulse rolling holes, containing a mandrel, on the Central longitudinal axis of which are placed made in the form of rods in the form of rods of a waveguide and firing pin, the last of which is installed with the possibility of impact on the waveguide to transmit periodic pulsed load, and it is equipped with interchangeable deforming tools, mounted on radially located plungers, mounted on the plunger packages of Belleville springs to ensure the application of static load normal about to the surface to be treated and a helical compression coil spring for acting on the free end of the waveguide, the surface of which is conical and located in contact with the free ends of the plungers [2].

The well-known interchangeable deforming tool is characterized by limited control capabilities in creating heterogeneous hardened layers and regular microrelief of the machined surface, as well as the complexity of the design and low productivity due to the small number of deforming elements.

The objective of the invention is to expand the technological capabilities of pulsed processing by surface plastic deformation through the use of a deforming tool with a large number of deforming elements evenly spaced around the entire circumference of the machined hole, which allows to increase processing productivity, improve the quality of the machined surface, control the depth of the hardened layer and the microrelief of the inner surface and reduce manufacturing costs due to simplicity design.

The problem is solved using the proposed deforming tool for pulse hardening of holes, containing disk-shaped springs assembled in a bag, made with an end conical surface, radial grooves and a central hole, a rod on which disk springs are located with the possibility of their longitudinal movement and change of their end cone angle surfaces and strikers, while the Belleville springs are made with the possibility of perception of the impulse load from the striker, deflection by f, increase their diameter and ensure the direction of the pulsed load normal to the work surface, while the magnitude of the deflection of the Belleville springs f is determined from the following expression:

F = 0.5 (D _Z -2h-d) tgα _p -0.5 (D _T -d) tgα _CB ,

where D _Z is the diameter of the workpiece’s hole, mm;

h - tightness during hardening, mm;

d is the diameter of the disk spring hole, mm;

α _p and α _CB - the cone angle of the end surface of the cup spring, respectively, in the working loaded and free states, deg .;

D _T is the outer diameter of the cup spring in a free unloaded state, mm.

The essence of the proposed design of the deforming tool is illustrated by drawings.

Figure 1 presents a diagram of the processing of pulse hardening using the proposed deforming tool, a longitudinal section, deforming tool - Belleville springs in a free unloaded state; figure 2 is the same, Belleville springs in a loaded state; figure 3 - the same combined longitudinal section, Belleville springs in free unloaded (above) and loaded (below) states; figure 4 - deforming tool is a Belleville spring with radial grooves and a Central hole, a longitudinal section and an end view, a dashed line shows the position of the spring in a loaded working condition; figure 5 is a design variant of a Belleville spring with less stiffness compared with the spring shown in figure 4; in Fig.6 is a variant of the design of a Belleville spring with a smaller area of the peripheral working surface compared with the spring shown in Fig.4.

The proposed deforming tool is used for surface plastic deformation of the inner surface of the holes of the workpieces using periodic pulsed load on the tool.

The proposed tool is installed on the mandrel 1 in the form of a sleeve, in the hole of which the striker 2 is placed with the possibility of free longitudinal movement in it. The firing pin 2 is freely mounted on a sliding fit on the central rod 3. The mandrel 1 and the rod 3 are rigidly connected to each other (not shown) and perform synchronous longitudinal movement S _PR when processing the workpiece hole. On the rod 3 with the possibility of longitudinal movement is installed a deforming tool consisting of a package of Belleville springs 4 with radial grooves and a central hole.

The deforming tool is made of Belleville springs 4 by cutting radial grooves with the formation of cantilevers arranged at an acute angle to the longitudinal axis of the pushers, with deformation elements 4 ^/ mounted on their periphery (see Figs. 1-3, 6). The deforming elements 4 ^{/ are} made of hard alloy or other wear-resistant material, mounted on the pushers by known methods and have rounded tops. Alternatively, the deforming elements 4 ^/ can serve as hardened peripheral ends of the pushers (see Fig.4-5).

The end surface of the Belleville springs 4 is conical with an inclination angle α _CB to the central axis when the spring is in a free unloaded state. Belleville springs 4 are located on the rod between the end face of the flange 5, rigidly mounted on the rod 3, and the striker 2. When moving the striker 2 from right to left, according to Fig.1-3, the Belleville springs 4 take on a periodic impulse load P _them striker 2, due to which they move to the flange 5 and bend by a value f, increasing along the outer diameter D _T.

The total longitudinal periodic impulse load P _{IM of the} striker is perceived by the whole package of Belleville springs and is evenly distributed to each spring. This means that each disk spring 4 through the pushers has a reinforcing effect with a pulsed load P _IM ^H directed along the normal to the surface to be treated (see figure 3).

The maximum attainable outer diameter D _T ^{max of the} deformed disk spring is

D _T ^max = D _T + 2z + 2h,

where D _T is the outer diameter of the cup spring in a free unloaded condition, mm;

z - guaranteed clearance required for free entry of the device into the hole to be machined, mm;

h is the tightness necessary for hardening, mm

However, the deforming elements of the spring do not reach the maximum diameter D _T ^max , due to the fact that the latter is larger than the diameter of the hole to be machined D _З , due to this, an interference fit h is created, while all deforming elements of the spring are in contact with the surface to be treated, i.e. the spring becomes available and hardening of the inner surface of the workpiece is realized.

As a mechanism for pulse loading of Belleville springs, a hydraulic pulse generator [2-3] or other known design (not shown) is used.

Belleville springs 4 can be made according to GOST 3057-79 from steel 60C2A (or other spring steel according to GOST 14963-78) with different radial grooves (see Figs. 4-6) and various sizes of parts of the peripheral surface of the 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.

The magnitude of the deflection of Belleville springs f depending on the geometric dimensions of the device and the hole being machined is determined by the formula

f = 0.5 (D _Z -2h-d) tgα _P -0.5 (D _T -d) tgα _CB ,

where D _Z is the diameter of the workpiece’s hole, mm;

h is the tightness necessary for hardening, mm;

d is the diameter of the disk spring hole, mm;

α _p and α _CB - the cone angle of the Belleville spring, respectively, in the working loaded and free states, deg .;

D _T is the outer diameter of the cup spring in a free unloaded state.

During processing, the workpiece receives a rotation of V _s , and the deforming tool for hardening receives the movement of the longitudinal feed S _pr along the axis of the workpiece. During the input of the deforming tool into the hole to be processed, the deforming disk springs 4 are in a free state and their outer diameter is less than the inner diameter of the hole to be processed; the number of Belleville springs 4 in the bag depends on the specific processing conditions and technical requirements for the surface to be treated, it is established experimentally taking into account the design features. In order to reduce friction between the ends of adjacent disk springs 4, thin spacers, for example, made of fluoroplastic (not shown), can be installed.

On the extreme to the striker 2, the Belleville spring 4 is affected by the striker 2, connected to a pulse loading mechanism (not shown) in the form of a hydraulic pulse generator [3-4].

A periodic pulsed load P is applied to _them in the direction of longitudinal feed and, thanks to the design features of the Belleville springs, they are directed normal to the surface to be treated.

Periodic impulsive load P _them should be larger than the total force required to deform the Belleville springs and the force required for hardening. The removal of the striker after impact in the initial position (according to Fig.1-3, to the right) is carried out due to the elasticity of the disk springs and return them to their original free state.

As a result of the impact of the striker 2 at the end of the disk spring package, the latter act on the surface to be machined with a cycle defined by a hydraulic pulse generator. The ability to rationally use the energy of shock waves is determined by the size of the instrument.

The depth of the hardened layer processed by the proposed deforming tool 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 deforming tool, experimental studies of the processing of the liner using a special stand. 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 pulsed force acting on the tool was P _them = 255 ... 400 kN. Billets made of steel 40X; initial hardness of “raw” samples is HV 270 ... 280. The depth of the layer hardened by pulsed processing 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 deforming tool, 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.

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 the tool - Belleville springs. 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 proposed tool 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 special tool with a large number of deforming elements, which allows to increase productivity and reduce manufacturing costs, due to the simplicity of design.

Information sources

1. A.S. USSR 171293 A1, MKP V24V 39/02, 06/22/1965 - 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. Kirichek A.V., Lazutkin A.G., Soloviev D.L. Static-pulse processing and equipment for its implementation // STIN, 1999, No. 6. - S.20-24.

Claims (1)

A deforming tool for pulse hardening of holes, containing disk-shaped springs assembled in a bag, made with an end conical surface, radial grooves and a central hole, a rod on which disk springs are located with the possibility of their longitudinal movement and changing the cone angle of their end surface and strikers, while Belleville springs are made with the possibility of perception of the impulse load from the striker, deflection by f, increasing their diameter and ensuring the direction of the impulse load ki along the normal to the surface being treated, characterized in that the deflection value of the Belleville springs f is determined from the following expression:
f = 0.5 (D ₃ -2h-d) tgα _p -0.5 (D _T -d) tgα _CB ,
where D ₃ - the diameter of the machined hole of the workpiece, mm;
h - tightness during hardening, mm;
d is the diameter of the disk spring hole, mm;
α _p and α _CB - the cone angle of the end surface of the cup spring, respectively, in the working loaded and free state, deg .;
D _T is the outer diameter of the cup spring in a free unloaded state.

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