RU2623567C1 - Method of rolling parts with curvilinear surface - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: reverse rolling of a stack, consisting of punch and matrix die with heated sheet between them, is carried out. In the first pass, the reduction is 10… 20%, in the second - 30…40%, in the third - 40…60% of the total absolute reduction.

EFFECT: roll bite of the stack is improved, that provides precise shape parameters and geometric dimensions of parts with a curvilinear surface.

2 dwg, 1 ex

Description

The invention relates to the processing of metals by pressure, in particular the production of metal curved surfaces from sheet metal.

A known method for the manufacture of bottoms from sheet blanks, including run-in blanks installed in the template on the centering unit, in a spiral with the help of forming rollers (see AS USSR No. 1400736, B21D 51/08, publ. 1988).

The disadvantage of this method is the uneven deformation of the workpiece and, as a result, obtaining the shape and size of the finished product with deviations from the set, as well as the complexity of its design.

Closest to the proposed method is a method of rolling parts with a curved surface, including rolling a package consisting of a punch and a matrix with a heated sheet blank located between them. Moreover, to give the required radius of the curvilinear surface, a packet of a punch and a matrix with a heated billet placed between them is rolled between the rolls of the working stand of the rolling mill (see certificate on p. M. No. 12537, B21D 51/08, publ. 2000).

The disadvantage of this method is to obtain the shape and size of the finished product with deviations from the specified parameters.

The problem solved by the present invention is to improve the quality of parts with a curved surface, namely obtaining more accurate shape parameters and geometric dimensions, reducing the deformation force, as well as improving the plastic properties of the deformed workpiece.

The problem is solved in that in the known method of rolling parts with a curved surface, including rolling a package consisting of a punch and a matrix with a heated sheet blank located between them, according to the invention, the rolling is carried out reversely in at least three passes, and in the first pass the compression is 10 ... 20%, in the second - 30 ... 40%, in the third - 40 ... 60% of the total absolute compression.

The technical result, which provides a solution to the problem, is to create conditions for more reliable capture of the entire package by rolls and conditions for uniform deformation of the workpiece in each reverse pass, reduce the deformation force and increase the ductility of the metal due to the fractional deformation.

Based on the analysis of known sources of information, we can conclude that for a specialist the inventive method of rolling metal does not follow explicitly from the prior art, and therefore meets the condition of "inventive step".

The invention is illustrated by drawings, where:

- in FIG. 1 shows a rolling scheme of a bag consisting of a punch and a die with a heated sheet blank located between them;

- in FIG. 2 shows a diagram of a reversible rolling of a bag with absolute reductions increasing in each pass.

The inventive method for rolling parts with a curved surface is implemented by the following package rolling scheme, where in FIG. 1-2 marked positions:

1 - matrix;

2 - sheet blank;

3 - an annular protrusion;

4 - concave surface of the annular protrusion;

5 - a punch;

6 - convex surface of the punch;

7 - upper roll;

8 - lower roll;

h _zag is the thickness of the workpiece;

h _det is the depth in the curved surface of the part;

h _punch - the height of the punch;

h _mat - the depth of the matrix, taking into account the wall thickness;

H _Pak - the thickness of the package;

ΔH _i - absolute compression of the package in the i-th passage;

R is the radius of the roll.

The proposed rolling method is implemented as follows.

The matrix 1 (Fig. 1) with a sheet billet 2, placed on an annular protrusion 3, is heated in a rolling hearth furnace until the metal naturally softens. The workpiece 2, softening, evenly settles to the surface 4 of the protrusion 3 of the matrix 1. To obtain the final curved surface, the punch 5 with a convex surface 6 is applied to the workpiece 2, which is located on the concave surface of the matrix 1.

To give the required radius of the curved surface, the package of the punch 5 and the matrix 1 with the softened blank 2 placed between them is rolled between the rolls 7 and 8 of the mill stand. Rolling is carried out reversely, at least in three passes, and in the first pass the compression is 10 ... 20%, in the second - 30 ... 40%, in the third - 40 ... 60% of the total absolute compression.

As a result of small reductions, the workpiece is gradually deformed, which prevents its displacement in the package and leads to an increase in the plastic properties of the workpiece metal due to fractional deformation. This will help to obtain a more accurate shape of the curved surface and the geometric parameters of the part, as well as reduce the strain.

An example of a specific implementation.

For the manufacture of a metal part with a curved surface with an inner diameter of 2420 mm, depth h _det = 200 mm and a wall thickness of 40 mm, a round billet of steel 09G2S with a diameter of 2500 mm and a metal thickness h _zag = 40 mm was used.

The matrix (Fig. 2) with a sheet blank placed on an annular protrusion was heated in a rolling hearth furnace until the metal naturally softened, to a temperature of 900 ° C. Then a punch with a height h _punch = 200 mm with a protrusion with a convex surface was placed on a workpiece placed on the concave surface of the matrix with a depth taking into account the wall thickness h _mat = 240 mm. The thickness of the bag was h _pack = 480 mm.

To give the required radius of the curved surface, a package consisting of a punch and a matrix with a softened blank located between them was rolled in a working stand of a rolling mill between rolls with a radius of R = 600 mm. Rolling was carried out reversely in three passes with reductions equal to 20% of the total absolute reduction in the first pass, 30% in the second and 50% in the third. The absolute reductions in the respective passages were: ΔH ₁ = 40 mm, ΔH ₂ = 60 mm, ΔH ₃ = 100 mm.

Thus, during reverse rolling, the reliability of the whole process is increased due to the stable capture of the package by the rolls, which allows to obtain higher quality parts with curved surfaces, with more accurate shape and geometric dimensions, and also reduced deformation forces in each pass. In addition, as a result of repeated deformation of the package, the deformation of the workpiece is fractional, which allows to increase the ductility of the wrought metal and make it possible to obtain parts with a curved surface from high-strength materials.

Based on the foregoing, we can conclude that the claimed method is workable and eliminates the disadvantages that occur in the prototype, which is confirmed by an example implementation. Accordingly, the claimed solution may be applicable in the rolling industry, and therefore, meets the condition of "industrial applicability".

Claims (1)

A method of manufacturing a part with a curved surface, including rolling a package consisting of a punch and a matrix with a heated sheet billet located between them, characterized in that the package is rolled reversely in at least three passes, and in the first pass, rolling is carried out with compression 10 ... 20%, in the second - 30 ... 40%, and in the third - 40 ... 60% of the total absolute reduction.

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