EA013828B1 - Method for manufacturing of cylindrical parts of internal combustion engines - Google Patents

Abstract

The invention relates to mechanical engineering, in particular to engine manufacturing and can be used at plants manufacturing diesel engines, e.g. D100, bushings and jackets as spare parts. A method is mostly related to manufacturing of bushings and jackets and includes pre-mechanical working, local speed heating of part zones, which are installed at distances from future openings, part cooling and further mechanical processing with making of openings. Local speed heating is realized up to temperature of 600-720°C, besides heating zones are symmetrically located relative to future openings and are equidistant along generatrix from edges of future holes at the distances equal to 0.9-2.2 of opening radius. At that width of every heating zone makes 1.0-2.0 radius of future hole, and length corresponds to central angle of 40-120°. Simultaneously with heating of local zones, subcooling of zones located between edges of future holes and local zones is carried out. The technical result is aimed at enhancing fatigue and corrosion-fatigue strength of cylindrical parts with transverse holes.

Description

The invention relates to mechanical engineering, in particular to engine building, and can be used in factories manufacturing diesel engines, for example D100, bushings and cylinder shirts for spare parts.

A known method of manufacturing cylindrical parts of internal combustion engines with hardening of cylinder shirts of a D100 diesel engine, in which, after machining, the surface at the openings of the cylinder shafts is rolled around (see Technological process for machining cylinder shirts, No. 081.01140.30.588, Lublin Foundry and Mechanical Plant, 1988) .

A disadvantage of the known method of manufacturing cylindrical parts is the shallow depth of the zone of residual compressive stresses.

There is also known a method of hardening cylinder shirts, in which, after preliminary machining and hole making, volumetric or surface hardening is performed (see RB Heywood, Designing for Fatigue, M., 1969, p. 381).

A disadvantage of the known method of hardening shirts and cylinders is to induce unacceptable deformation and residual tensile stresses.

The closest technical solution is a method of manufacturing cylindrical parts of internal combustion engines, in which, after preliminary machining, local high-speed heating to a temperature of 720-750 ° C of zones located at a distance of 1.5-2.0 radii of the future hole from its center at the central angle of 80-120 ° in the direction of the axis coinciding with the maximum tensile loads (see 8 см, No. 1004478, S21I 1/42, 1983).

The disadvantages of this method are due to the selected temperature range at which phase transformations and a local increase in hardness occur, which causes difficulty in subsequent machining. In this method, the maximum effect of strengthening the zone of the holes is not achieved due to the lack of communication of the geometric parameters of the heating zone (width and length).

The technical result that can be obtained by using the method according to the invention is to increase the fatigue and corrosion-fatigue strength of cylindrical parts with transverse holes.

The specified technical result is achieved in a method for manufacturing cylindrical parts of internal combustion engines, mainly bushings and shirts, including preliminary machining, local rapid heating of the parts zones located at distances from future holes, cooling the part and subsequent machining with holes, while local high-speed heating is carried out to a temperature of 600-720 ° C, and the heating zones are symmetrically located from future holes and are equally removed about the generatrix from the edges of future holes at distances equal to 0.9-2.2 of the radius of the hole, the width of each heating zone being 1.0-2.0 of the radius of the future hole, and the length corresponds to a central angle of 40-120 °.

In addition, simultaneously with the heating of the local zones, the zones located between the edges of the future holes and the local zones are reinforced, which makes it possible to expand the zone of residual compressive stresses along the generatrix of the cylinder.

The tightening of adjacent zones allows to increase the level of heat-shrinkable deformations and residual compressive stresses along the generatrix of the cylinder.

The proposed method for the manufacture of cylindrical parts of internal combustion engines is illustrated in the drawings.

In FIG. 1 shows the distribution of stresses in the shirts of cylinders of diesel engines of type D100 along a generatrix, in FIG. 2 shows a scan of the shirt along the outer diameter, where 1 is the shirt of the cylinder; 2 - adapter hole; 3 - heating zone.

The method is as follows.

For shirts of diesel cylinders of type D100 made of steel with an outer diameter of 276 mm, a wall thickness of 16.5 mm, a height of 420 mm, and having three holes 46 mm in the middle part in height, during processing to make holes to create residual compressive stresses, local rapid heating, for example, by high-frequency currents, of areas 40x220 mm in area at a distance of 20-30 mm from the proposed edges of the holes. After reaching the wall heating temperature of 600-720 ° C, air cooling is performed. The cooling of parts in air after local high-speed heating leads to the appearance of a zone of residual compressive stresses, which makes it possible to obtain a stable increase in fatigue and corrosion-fatigue strength. Then carry out subsequent machining with holes. Moreover, the maximum residual compressive stresses on the surface of the holes in the zones of maximum tensile stresses from working loads reach 60 kgf / mm ² and are distributed over the entire wall thickness and at a distance of 20-30 mm along the generatrix from the surface of the hole. The increase in the limited endurance limit based on 5x10 ⁶ cycles in a 1% solution of sodium chloride is 1.4-1.6 times compared with hardening by rolling the surface of the rollers.

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The estimated technical and economic effect of the introduction of the proposed method for the manufacture of cylindrical parts with transverse holes as applied to the shirts of D100 type diesel cylinders at the Russian Railways factories for the production of spare parts will be about 40 million rubles / year for the operating diesel fleet.

The application of the proposed method for the manufacture of bushings and cylinder shirts of diesel engines of type D100 allows you to get at the edges of the holes a zone of residual compressive stresses of the required depth, which significantly increases the fatigue and corrosion-fatigue strength of these parts.

Claims (2)

CLAIM 1. A method of manufacturing cylindrical parts of internal combustion engines, mainly sleeves and shirts, including pre-machining, local high-speed heating of parts, located at distances from future holes, cooling parts and subsequent machining with the holes, characterized by the fact that local high-speed heating carry out up to a temperature of 600-720 ° C, with the heating zones symmetrically located from the future holes and equally removed along the generatrix from the edges of the future from ERSTU distance equal to 0,9-2,2 hole radius, wherein the width of each heating zone is 1.0-2.0 radius future hole, and the length corresponds to the central angle 40-120 °. 2. A method of manufacturing cylindrical parts according to claim 1, characterized in that simultaneously with the heating of the local zones, the zones located between the edges of the future holes and the local zones are intensified.