RU2325451C2 - Method of tool steel properties improvement - Google Patents

Abstract

FIELD: technological processes, non-cutting shaping.

SUBSTANCE: invention is related to metals non-cutting shaping for improvement of tool steel resistance and may be used in aircraft building, shipbuilding and other industries. In order to improve tools resistance, stocks are subjected to plastic deformation, first by twisting to shear deformation on the stock surface, than by collapsing to logarithmic compression strain, accumulated plastic deformation is determined by the following dependence:

where e_c is logarithmic compression strain; γ₀ - shear deformation on the stock surface, and then the stock is thermally treated.

EFFECT: improves tool steels resistance.

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Description

The invention relates to the processing of metals by pressure with respect to increasing the durability of tool steels and can be used in aircraft, shipbuilding and other industries.

A known method [1] of processing a workpiece made of tool steel, including simultaneous upsetting with torsion of the workpiece to accumulate deformation, providing the greatest resistance to steel.

The disadvantage of this method is the limited ability to increase the resistance of tool steel.

The invention is aimed at providing a higher degree of increase in tool steel durability by superimposing draft deformation on shear deformation in the technological process.

This is achieved by the fact that the workpiece made of tool steel is first subjected to torsional deformation to shear deformation on the surface of the workpiece, and then to sag to a logarithmic compression deformation, and the accumulated plastic deformation is determined by the following relationship

where e _c is the logarithmic compression strain; γ ₀ - shear strain on the surface of the workpiece.

The essence of the proposed method is as follows. The preforms made from tool steel rods are first subjected to torsion to a shear strain γ ₀ on the surface of the preform, then they are deposited until the logarithmic compression deformation e _s , and the accumulated plastic deformation is determined by the formula (1).

The shear strain at the point of the cross section of the workpiece, the coordinate of which is determined by a radius ρ in the range from 0 to the outer radius of the workpiece r ₀ , is determined by the formula

. Логарифмическая деформация сжатия определяется по соотношениюwhere φ is the absolute angle of rotation of the end sections spaced apart from each other at a distance

. Logarithmic compression strain is determined by the ratio

where h ₀ , h - the initial and current height of the workpiece.

The present invention can be used quite effectively to increase the durability of cylindrical tools such as reamers, end and cylindrical mills, countersinks. For these types of tools, the cutting blades are on a cylindrical surface. In this regard, to estimate the shear strain on the surface of the workpiece by the formula (2), it is necessary to take ρ = r ₀ , i.e.

where γ ₀ is the shear strain on the surface of the workpiece.

The optimal value of the total strain in accordance with formula (1) is experimental for each shear value γ ₀ . Determine the value of compression deformation e _s , at which the maximum resistance of tool steel is established. Further, the deformed workpieces are subjected to heat treatment according to the temperature regime appropriate for each tool steel.

. После чего они перед термообработкой подвергались кручению на испытательной машине КМ-50 до деформации сдвига γ₀=0,05; 0,10; 0,15; 0,20; 0,25; 0,30; 0,35; 0,40; 0,45.An example of the implementation of the proposed method is considered on low alloy tool steel 9XC. Billets with heads and a working diameter of d ₀ = 2r ₀ = 15 mm and an estimated length were made from the bars of this steel.

. Then, before heat treatment, they were subjected to torsion on a KM-50 testing machine until shear strain γ ₀ = 0.05; 0.10; 0.15; 0.20; 0.25; 0.30; 0.35; 0.40; 0.45.

Table 1 shows the values of the angle φ in rad., On which billets were twisted with a radius r ₀ = 7.5 mm to obtain the indicated calculated values of γ ₀ . The angle φ was determined by the formula obtained from (4)

Table 1 γ ₀ 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 φ, glad. 0.5 1,0 1,5 2.0 2,5 3.0 3,5 4.0 4,5

Further, short samples with a height of h ₀ = 25 mm were made from these blanks. Their precipitation for each shear strain γ _{0 was} carried out before the strains e _c = 0.10; 0.15; 0.20; 0.25; 0.30; 0.35; 0.40; 0.45; 0.50; 0.55. Table 2 presents the values of the current height h, to which it is necessary to compress the workpieces. In this case, the current height was calculated according to the formula obtained from (3)

Table 2 e _c 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 h mm 22.62 21.52 20.47 19.47 18.52 17.62 16.76 15.94 15.16

Table 3 presents the accumulated plastic strain values e calculated by the formula (1).

To establish the effect of increasing the resistance of steel, tests were made of deformed cutter blanks with appropriate heat treatment (hardening and subsequent tempering).

Tests of the cutters showed that the resistance of steel depends on the accumulated plastic deformation e. An increase in resistance occurs to some optimal value e _opt , after which the resistance begins to decrease.

, при которой стойкость стали становится наибольшей -

, и соответственно рассчитывают по формуле (1) накопленную деформацию е. Оптимальную накопленную деформацию е_опт, соответствующую максимальной стойкости T_max из всех наибольших стойкостей

, устанавливают статистической обработкой опытных данных. В результате установлено, что для исследованной стали е_опт=0,394 (е_с=0,31; у₀=0,42).Moreover, for each shift value γ ₀ presented in Table 1, the compression strain is determined experimentally

at which the resistance of steel becomes the greatest -

, and, accordingly, the accumulated deformation e is calculated according to the formula (1). The optimal accumulated deformation e _opt corresponding to the maximum resistance T _max of all the maximum resistance

, establish the statistical processing of experimental data. As a result, it was found that for the studied steel, e _opt = 0.394 (e _c = 0.31; y ₀ = 0.42).

The increase in steel resistance relative to resistance by the prototype method amounted to 1.17 times (17%), which is significant enough for cutting tools. The temperature conditions of heat treatment in the compared methods were the same.

The application of the invention in industry will effectively increase the durability of tools (cutting and measuring).

Information sources

1. RF patent No. 2252269, C21D 8/00, 7/00, 05/20/05, Bull. Number 14.

Claims (1)

A method of processing a workpiece made of tool steel, including deformation of the workpiece to the required accumulated deformation and heat treatment, characterized in that in order to maximize the resistance, the workpiece is first subjected to torsional deformation to shear deformation on the surface of the workpiece, and then to sag to a logarithmic compression deformation, and the accumulated plastic deformation is determined by the following relationship:

, where e _c is the logarithmic compression strain; γ ₀ - shear strain on the surface of the workpiece.