RU2591980C1 - Method of hardening of tillage machine working tools - Google Patents

Abstract

FIELD: agriculture.

SUBSTANCE: invention relates to agricultural machine building, particularly to the tillage machines, and can be used in production and recovery of plowshares, cultivator blades and flat cutting knives, subjected to abrasive wear. Method of hardening of tillage machine working tools involves intermittent application of hard wear-resistant alloy deposition on surface of the Jet knife with limitation of welding zones. Hard alloy are arranged in zones of welding on the blade in the form of etched in its material groups hemispheres diameter equal to thickness of the base of the blade. Centres of the hemispheres in each group are arranged with pitch equal to their diameter, along an arc of logarithmic curve, convex towards the knife blade. Group of the hemispheres are aligned parallel shifts along the knife blade with a pitch which is calculated depending on the blade length and width of the Jet of the blade so that the ratio of the width of zones of welding to step ranges from 1:2 to 2:3.

EFFECT: method of strengthening of higher wear resistance of soil-cutting parts and their operation effect self-sharpening blades with their toothed shape with optimum parameters for reduction of resistance in soil treatment.

1 cl, 3 dwg

Description

The invention relates to agricultural machinery, in particular to tillage machines, and can be used in the manufacture and restoration of plowshares, cultivating paws and flat-cutting knives subjected to abrasive wear.

A known method of hardening plowshares and other similar parts by continuous deposition on their working surface of an alloy (sormeth) of greater hardness than the base metal of the parts. This allows you to significantly increase their wear resistance (S. Sidorov. Increasing the resource of soil-cutting organs with surfacing alloys / S. Sidorov, A. Sidorov // Mechanization and Electrification of Agriculture. - 2003. - No. 9. - P. 20- 22).

The known method has the following disadvantages: the effect of self-sharpening of the blades is manifested only on some types of soils of medium moisture, and on hard, stony soils and soils of high humidity, the blades become dull, and the deposited layer is painted, which leads to accelerated wear of soil-cutting parts, increased traction resistance of tools and unproductive hard alloy consumption. The process of continuous surfacing is laborious and is associated with a large consumption of surfacing material. In addition, continuous surfacing does not allow to obtain the serrated shape of the blades of the working bodies in the process of their operation.

There is also a method of hardening the working bodies of tillage machines (a.s. 12220150 USSR, class A01 B 15/04, B23K 9/04, claimed 22.07.83, publ. 30.12.86, bull. No. 48), providing for the formation of surface details of the recesses, followed by filling them with a hard alloy by the method of electric arc welding. Using the known method allows to increase the wear resistance of parts, to improve the self-sharpening of their blades and to reduce the cost of hardening in comparison with continuous surfacing.

However, this method does not allow to obtain in the process of operation of the working bodies the serrated shape of their blades with specified parameters that provide a decrease in resistance during soil cultivation, which is its significant drawback.

Closest to the technical nature of the claimed invention and selected for the prototype is a method of obtaining wear-resistant blades of the working bodies of tillage tools (A.S. 461721 of the USSR, class A01 B 15/04, declared 25.02.64, publ. 28.02.75, bull. . No. 8), which provides for the location of harder metal on a smooth surface of the blades intermittently and parallel to the cutting edge with the subsequent restriction of the weld zone. The known method allows to increase the wear resistance of parts, to improve self-sharpening and to obtain a wavy shape of the blades when they wear.

The disadvantages of this method: a smoothly deposited layer of solid metal is not firmly held on the surface of the part. In addition, the absence in the known method of clear instructions on the parameters of the limitation and the shape of the weld zone does not ensure the receipt during operation of serrated blades with optimal parameters of its protrusions and depressions to reduce resistance during soil cultivation.

The basis of the present invention is the technical task of creating a new method of hardening the working bodies of tillage machines with the achievement of a technical result - increasing the wear resistance of soil-cutting parts and ensuring the effect of self-sharpening of the blades during their operation with the formation of their serrated shape with optimal parameters, which helps to reduce resistance during soil cultivation.

The problem is solved due to the fact that the proposed method of hardening the working bodies of tillage machines provides for intermittent deposition of a hard wear-resistant alloy by surfacing on the surface of a soil-cutting knife with restriction of the surfacing zones, while the hard alloy is placed in the surfacing zones on the knife in the form of hemisphere groups melted into its material diameter equal to the thickness of the base of the knife, and the centers of the hemispheres in each group are placed with a step equal to their diameter along the arc of the logarithmic curve convex in the side of the knife blade, and the hemisphere groups are combined by parallel transfers along the knife blade with a step that is calculated depending on the length of the blade and the width of the soil-cutting knife in such a way that the ratio of the width of the surfacing zones to the step is from 1: 2 to 2: 3.

New significant features:

1. The hard alloy is placed in the areas of surfacing on the knife in the form of hemisphere groups fused into its material with a diameter equal to the thickness of the knife base.

2. The centers of the hemispheres of the deposited hard alloy in each group are placed with a step equal to their diameter along the arc of a logarithmic curve convex towards the knife blade.

3. The hemispherical groups of the deposited hard alloy are combined by parallel transfers along the blade of the knife with a step, which is calculated depending on the length of the blade and the width of the soil-cutting knife in such a way that the ratio of the width of the surfacing zones to the step is from 1: 2 to 2: 3.

These new significant features in conjunction with the known allow to obtain a technical result achieved by using the invention.

The invention is illustrated in FIG. 1-3.

In FIG. 1 shows a hardening scheme of a soil-cutting knife according to the proposed method with the designation of the necessary parameters, FIG. 2 is a section A-A of FIG. 1, in FIG. 3 - arrangement of the centers of the hemispheres of a group of hard wear-resistant alloy along the arc of the logarithmic curve f (x), where 1 is the soil-cutting knife, 2 is the initial blade of the knife, 3 is the hemisphere of the wear-resistant hard alloy, 4 is the line of the knife blade formed in as a result of wear during operation, 5 — knife tip, a — width of the surfacing zones, b — distance between adjacent surfacing zones, c — thickness of the knife base, d — hemisphere diameter of the deposited hard alloy, t — spacing of the hemispheres of the wear-resistant hard alloy Av group, B - width pochvorezhuschego knife, L - the length of the original blade, S - a step of combining a parallel displacement of adjacent groups hemispheres of the deposited carbide, f (x) - Arc logarithmic curve, along which are placed center of the hemisphere of the deposited carbide, r _i - the radius vector of the logarithmic spiral describing the shape of the section of the line of the blade of the knife between adjacent zones of surfacing, formed as a result of its wear during operation.

The proposed method of hardening the working bodies of tillage machines is carried out in this sequence. Preliminary calculate the location parameters of the solid wear-resistant alloy on the soil-cutting knife according to the following formulas:

,

,

where Z is the number of hemisphere groups of the deposited hard alloy;

L is the length of the original knife blade;

B is the width of the soil-cutting knife,

, $$S=\frac{L}{Z-(\mathrm{one}-2K)}$$

,

where S is the step of combining by parallel transfer of neighboring groups of hemispheres of the deposited hard alloy;

L is the length of the original knife blade;

K is the deposition coefficient, taking into account the type of hardened working body and the type of cultivated soil (for example, for cultivator-plane cutter knives intended for processing medium loamy chernozem, K = 0.25);

a = 2K

where a is the width of the surfacing zones;

K is the surfacing coefficient;

S is the step of combining by parallel transfer of neighboring groups of hemispheres of the deposited hard alloy,

b = S - a,

where b is the distance between adjacent areas of surfacing;

S is the step of combining by parallel transfer of neighboring groups of hemispheres of the deposited hard alloy;

a is the width of the zones of surfacing,

where f (x) is the arc of the logarithmic curve along which the centers of the hemispheres of the deposited hard alloy are placed;

ν is the deformation index of the soil;

P _cr - critical pressure on the soil;

x is the current abscissa of the logarithmic curve;

a - the width of the zones of surfacing;

f _t - coefficient of friction of the soil according to the material of the soil-cutting knife;

G is the shear modulus of the soil.

According to the calculated parameters, a hard wear-resistant alloy is deposited onto the surface of the soil-cutting knife 1 by melting it (for example, by the electric arc method) into the knife material in the form of a group of hemispheres 3 with a diameter d equal to the thickness c of the knife base (see Fig. 1, 2). The hemisphere centers in the group are placed with a step t equal to their diameter d along the arc of the logarithmic curve f (x) of width a, convex towards the knife blade 2, starting from the toe 5 of the knife (see Figs. 1, 3). In this case, the surfacing zone is limited by the line of the blade 2 of the knife and the width a of the arc of the logarithmic curve f (x). Then, the remaining groups of hemispheres are surfaced, observing the condition of combining them with parallel transfers along the blade 2 of knife 1 with step S in such a way that the ratio of the width a of the surfacing zones to step S is from 1: 2 to 2: 3. The consumption of surfacing material with this ratio in intermittent surfacing is less than when it is continuously applied to the blade.

Surfacing a hard wear-resistant alloy according to the method of the invention can be carried out both manually and mechanically.

During operation of the knife, hardened by the proposed method, due to abrasive wear in the soil, its blade acquires a serrated shape with protrusions and depressions, shown by the dashed line in FIG. 1. Moreover, if the hardening parameters of the knife specified in the invention are observed during surfacing, the shape of the blade formed on the protrusions is described by the logarithmic curve f (x), and in the depressions by the logarithmic spiral, the equation of which in polar coordinates has the form:

, $$r_i=r_0{e}^{{\theta }_{i}tg\varphi }$$

,

where r _i is the radius vector of the logarithmic spiral;

r ₀ is the initial radius vector;

e - the basis of natural logarithms;

θ _i is the polar angle;

φ is the angle of internal friction of the soil.

In the interaction of such a serrated blade with the soil, the contact pressure concentrates on the hardened protrusions, contributing to the effective cleavage of the soil, at the same time it glides in the cavities between the teeth with minimal resistance. As a result of the redistribution of contact pressure and soil sliding along the blade, its cutting edge is self-sharpening. Chipping soil with the protrusions of the blade with its sliding and the effect of self-sharpening the cutting edge in the aggregate lead to a significant decrease in resistance during soil cultivation, and this reduces wear and increases the durability of soil-cutting parts. Thus, the technical result of the claimed invention is achieved.

Claims (1)

A method of hardening the working bodies of tillage machines, including intermittent deposition of hard alloy by surfacing on the surface of a soil-cutting knife with restriction of the surfacing zones, characterized in that the hard wear-resistant alloy is applied in the surfacing zones on the knife in the form of hemisphere groups fused into its material with a diameter equal to the thickness of the knife base, moreover, the centers of the hemispheres in each group are placed with a step equal to their diameter along the arc of a logarithmic curve convex towards the knife blade, and the groups of hemispheres are combined parallel translations along the blade of the knife with a pitch which depends on the blade length and width pochvorezhuschego knife so that the ratio of width to step deposition zones is 1: 2 to 2: 3.

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