RU2553124C2 - Hardening of metal parts of machines - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to surface hardening of assembly units and parts of the machines. The part is clamped from above and below by spinning pressure shafts fitted in the frame. Said part is placed on said spinning support shaft. Part is subjected to elastic bending. Elastically bent part is hardened on its convex stretched surface by means of surface plastic deformation appliance.

EFFECT: higher efficiency of hardening.

2 dwg

Description

The present invention relates to the field of machining in the manufacture or repair of metal parts of machines having relatively small thicknesses and capable of elastically bending.

A known method of hardening metal parts of machines with surface plastic deformation (PPD), which consists in creating internal compressive stresses in their surface layers. Hardening of metal parts of machines can be carried out by impact (bead-blasting, ultrasonic treatment, etc.), or static (rolling, smoothing, etc.) PPD.

When PPD shifts occur in the grains of metal parts, distortion of its crystal lattice, a change in the shape and size of grains, which contributes to the displacement of dislocations deep into the metal and prevents the development of microcracks. As a result of PPD, the surface layers of machine parts are compressed. At the same time, surface roughness decreases, strength, hardness and endurance of the surface layers of metal parts increase, which largely determine their operational properties [1, 2].

However, the PPD of metal parts, and especially parts made of high-strength steels and alloys, is a very time-consuming process.

The aim of the proposed invention is to increase the efficiency of hardening of metal parts of machines.

This goal is achieved in that before the start of hardening of the PPD, and during it, the metal parts are pre-elastically bent, and fixed in this position in a special device so that internal tensile stresses arise in the surface layers of the treated surface of the metal parts. Figure 1 shows a diagram of a device for hardening PPD metal parts of machines, increasing the efficiency of hardening. In figure 1, the numbers denote:

1 - hardened part;

2 - a supporting shaft;

3 - device PPD;

4 - clamping shafts, bending and fixing the hardened part 1;

5 - latches regulating the position of the clamping shafts 4 in the vertical or horizontal planes.

Improving the efficiency of PPD metal parts of machines is carried out in the following way. The device for fixing the hardened part 1 (see figure 1) has a frame structure with adjustable in vertical and horizontal planes by means of clamps 5 clamping shafts 4, clamping the part 1 along its edges from above and below. The clamping shafts 4 rotate around their longitudinal axes. Part 1 is placed on a support shaft 2 rotating around its longitudinal axis, elastically bent by the required value and fixed by means of clamps 5 by the pressure shafts 4 as shown in Fig. 1. Using the device PPD 3, part 1, relying on the support shaft 2, is hardened with a convex stretched surface. At the end of the RPM, the hardened part 1 is released from fixation. When released from elastic deformation in a metal part, its surface layers compressed as a result of PPD are further compressed. Induced in them internal compression stresses become more intense and extend to greater depths, which entails a more efficient hardening of the part.

Figure 2 shows the distribution of internal stresses in hardened PPD layers of pre-curved and non-curved parts. Figure 2 shows half of the parts above their neutral lines. In figure 2, numbers and letters denote:

6 - part not curved during PPD;

7 - detail elastically curved during PPD;

h ₁ - the depth of propagation of internal compression stresses in the part 6;

h ₂ - the depth of propagation of internal compression stresses in the part 7.

The distribution is obtained as a result of experimental studies by the method of measuring the microhardness of a material with the PMT-3 device of samples made of steel 40X, treated by shot peening.

The metal part 7, the surface layers of which were processed by PPD in the stretched bending state, has internal compression stresses (15% greater in absolute value and extending 21% greater depth (h ₂ > h ₁ ) in the surface layers (in the diagram depicted in FIG. 2, they have negative values) compared to the part 6 that was not bent during hardening. In the depth of the parts, near their neutral lines, internal tensile stresses are induced as a result of the RPD (they have positive values on the diagrams depicted in Fig. 2), od ako weighty influence on the strength characteristics of the components in this place do not have a tensile stress.

To exclude warping of metal parts as a result of PPD (bending of the ends of parts to the source of PPD), it is necessary to process the PPD of the part from the opposite surface.

Information sources

1. Odintsov L.G. Hardening and finishing of parts by surface plastic deformation: a Handbook. - M.: Mechanical Engineering, 1987. - 328 p.

2. Smelyansky V.M. Mechanics of hardening of parts by surface plastic deformation. - M.: Mechanical Engineering, 2002. - 300 p.

Claims (1)

A method of hardening metal parts of machines, including clamping the part from below and above along its edges by means of rotating clamping shafts installed in the frame, the position of which is regulated in the vertical and horizontal planes in the frame by means of clamps, the elastic bending of the part, which is placed on a rotating support shaft supported by the shaft and hardening of the elastically curved part from the side of its convex elongated surface using a device for surface plastic deformation.

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