RU2697306C1 - Matrix for pressing materials with low process plasticity - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to metal forming, namely, to design of matrices for pressing hard-to-deform materials with low process plasticity, particularly aluminum alloys. Matrix has three-dimensional bent working surface, which includes concave inlet section, conjugated with convex crimping section, smoothly changing into gaging belt, wherein the profile of the input and compression sections of the matrix are in form of surfaces of the second order, formed by rotation around the axis of the matrix of the curve, which consists of sections of a circle, an ellipse, a parabola, a hyperbola or a second-order polynomial.

EFFECT: higher quality of surface of press items out of plastic ones under conditions of thermodynamic cycle of pressing of aluminum alloys, including eutectic and hypereutectic silumin, as well as improvement of manufacturability of their pressing.

5 cl, 4 ex, 6 dwg

Description

The invention relates to the processing of metals by pressure, namely, to a tool for pressing metal materials.

The purpose of the invention is to improve the surface quality of press products made of materials with low technological ductility, in particular, insufficiently ductile under the conditions of the thermodynamic cycle of pressing aluminum alloys, including eutectic and hypereutectic silumins, as well as improving the manufacturability of pressing such materials.

The surface quality of the press products is the most pressing issue in their production, depending on the uniform distribution of deformation over the volume of the workpiece, the mechanical properties of the pressed material, its rheological characteristics under conditions of hot deformation, the rate of deformation, contact friction at the interface between the pressed material and the matrix, and other factors. One of the factors determining the quality and dimensional accuracy of the press products is the geometry of the matrix channel - the shape of its working surface forming the press product. The design of the matrix should ensure the quality of the press products and the manufacturability of the pressing process.

The multifactorial influence determines the many technical solutions for the design of both standard matrices and structural solutions for certain materials and types (types) of press products. At the same time, design features are very critical.

Typical pressing matrices with various shapes of the working surface are known: flat, conical, flat conical, radial, radial conical (Compression of heavy non-ferrous metals and alloys. Yu.F. Shevakin, L.M. Grabarnik, A.A. Nagaitsev. M .; Metallurgy, 1987.246 s.).

As noted above, standard solutions do not solve the quality problem of press products from a number of materials, especially with low technological ductility.

There are many known designs of the working surface of the matrix for pressing low-plastic materials:

- in the form of a double cone (ed. certificate. USSR No. 1810158),

- concave in radius (RF patent No. 2222407),

- with a convex profile of the crimp section, performed according to the function of the Gaussian probability integral (ed. certificate of the USSR No. 1391750),

- with a three-dimensional curved design of the input surface (EP No. 0430922; GB No. 1456735; Yu.P. Glebov, V. S. Gorokhov, M. F. Zakharov, - “Technology of light alloys”, 1975, No. 5, p. 23- 28) and others.

The application of these matrices, solving the problem of improving the surface quality of the press products for a particular material and type (type) of the press product, does not provide the necessary surface quality of the press products on other difficultly deformed materials with low technological ductility.

The closest to the proposed matrix in terms of technical nature and the achieved effect, adopted as a prototype, is a matrix with a three-dimensional curved working surface, having a concave inlet section, conjugated with a convex crimp section, smoothly turning into a calibrating girdle (S.V. Belyaev, I.M. Dovzhenko, RE Skolov, et al. Press technology. Lecture notes. Krasnoyarsk, SFU, 2007, 310 pp.).

The matrix does not provide the required surface quality of the press products from some difficult-to-deform materials with low technological ductility, in particular, from aluminum alloys, including eutectic and hypereutectic silumins.

The alleged invention is aimed at improving the quality of the surface of the press products of insufficiently plastic in the conditions of the thermodynamic cycle of pressing aluminum alloys, including eutectic and hypereutectic silumins, as well as improving the manufacturability of their pressing.

The technical result is achieved by the fact that in the known matrix with a three-dimensional curved working surface having a concave inlet section, conjugated with a convex crimp section that smoothly passes into the calibrating girdle, the profile of the input and crimp sections of the matrix are made in the form of second-order surfaces formed by rotation around axis of the matrix of the curve, consisting of sections of a circle, ellipse, parabola, hyperbola or polynomial of the second order, while:

- the height of the concave inlet portion is 5-20% of the outer diameter of the matrix D,

- the height of the convex crimp section is 3.5-35% of the outer diameter of the matrix D,

- the total height of the concave inlet and convex crimp sections is 15-55% of the outer diameter of the matrix D,

- the diameter of the circle d _c at the interface between the input and crimp sections is determined by the ratio d _c = d + (0,1 ÷ 0,6) × (Dd), where d is the diameter of the calibrating girdle (press product),

- the angles of inclination of the tangent at the beginning of the input section and at the interface between the input and crimp sections to the plane of the cross section of the press product are respectively from 20 ° to 75 ° and from 0.5 ° to 60 °.

The technical result is determined by the characteristics of the pressing process. Based on the fundamental theoretical concepts, contact friction makes it difficult to move metal near the walls of the container and matrix. In addition to contact friction, the channel profile of the matrix has a significant effect on the metal flow. Even in the absence of contact friction (theoretically idealized condition), the deformation of a simple shear during compression in the matrix channel leads to uneven deformation. When choosing a matrix design for pressing materials with low technological ductility, it is important to provide two conditions: the hydrostatic pressure in the deformation zone should be as large as possible, and the unevenness of the plastic flow in the press product as small as possible. The first condition provides a concave input portion of the matrix, the second is a convex crimp portion of the matrix. In this case, the profile of the convex crimp section has little effect on the pressing pressure, but significantly affects the surface quality due to the rotation of the pressed metal at the entrance to the calibrating girdle. Based on theoretical concepts, it is important to ensure the optimal profile of each section of the working surface of the matrix.

To determine the optimal profile of each section of the working surface of the proposed matrix 1 allows physical modeling by pressing a non-plastic metal 2 with a very low deformation rate through a model matrix 3 having a flat working surface, in the presence of a front washer of plastic metal in front of the pressed workpiece (Fig. 1 and Fig. 2). During the pressing process, the plastic metal of the front washer is assembled in the stagnant zone 4. At a low, far beyond the practical application, strain rate, sliding of the unplastic pressed metal under conditions close to equilibrium is carried out along the self-organizing boundary of the stagnant zone and the pressed metal. In FIG. 1 shows a macro section of an axial section in the area of the matrix when pressing a bar of 5 ∅25 mm from a container of ∅100 mm (drawing ratio 16), in FIG. 2 - macro section of an axial section when pressing a bar 6 ∅75 mm from a container ∅120 mm (drawing ratio 2.56). The self-organizing boundary in the section is a curve that is described with sufficient approximation by sections of a circle, ellipse, hyperbola or parabola, and the surface itself along which the slip occurs is a second-order surface formed by the rotation of this curve around the axis of the matrix. With a small draw (pressing a bar ∅70 mm from a container ∅100 mm with a draw ratio 2), the inlet surface may have a shape close to conical.

An analysis of the profile of the self-organizing sliding surface indicates the following.

The height of the concave inlet portion of the matrix is within h _x = (0.05-0.2) D, where D is the outer diameter of the matrix, as a rule, sufficient to provide the necessary hydrostatic pressure in the deformation zone and the integrity of the metal during pressing. Smaller _{hx values} correspond to a larger hood.

The height of the convex crimp section of the matrix within h _o = (0.035-0.35) D provides a sufficient reduction in simple shear deformation during compression in the matrix channel and the uniformity of plastic flow in the press product. With a decrease in the technological plasticity of the pressed metal, the height of the crimp section h _о should correspond to large values. With a larger hood, the height of the crimp section should also increase to reduce the uneven deformation in the channel of the matrix.

The total height of the concave inlet and convex crimp sections within h in _x + h _o = (0.15-0.55) D is sufficient to provide the two previous conditions and limits the total height of the matrix.

The diameter of the circle at the junction of the input and crimp sections in the ratio d _c = d + (0.1 ÷ 0.6) × (Dd), where d is the diameter of the calibrating girdle, is determined by the optimal ratio of the height of the input and crimp sections of the matrix.

The angle of inclination of the tangent at the beginning of the input section from 20 ° to 75 ° is selected within the range of actually applied angles. In the upper part of the matrix, as a rule, blunting up to 2 mm is performed, which prevents damage to the sharp edge during pressing.

The angle of inclination of the tangent at the junction of the input and crimp sections to the plane of the cross section of the press in the range from 0.5 ° to 60 ° is determined by the optimal form of conjugation of the input and crimp sections of the working surface of the matrix.

Case Studies

Example 1. Pressing a bar d25 mm from hard to deform powder aluminum alloy САС-1-50 from a container D100 mm with a draw ratio of 16.

The three-dimensional curved working surface of the matrix is formed along the real self-organizing boundary of the stagnant zone when pressing the SAS-1-50 alloy at low speed through a flat matrix in the presence of a front washer made of plastic metal in front of the pressed workpiece (Fig. 1).

The input section of the matrix is well described by the rotation around the matrix axis of the section of the parabola y ₁ = x ₁ ² / 2p, the focus and vertex of which lie on the axis of the matrix, where p is the parabola parameter equal to 76.4 mm. The height of the inlet section is 13.8 mm (13.8% D).

The crimped portion of the matrix is formed by rotation around the axis of the matrix of the portion of the ellipse y ₂ ² = b ² -b ² / a ² * x ₂ ² . The semimajor axis of the ellipse a = 4.99 mm, the minor b = 4.34 mm. The focuses of the ellipse lie on a straight line perpendicular to the axis of the matrix passing through the beginning of the calibrating girdle. The left vertex of the ellipse is located on its major axis at the beginning of the calibrating belt, and the axis of ₂ ellipses is separated from the calibrating belt at a distance of a = 4.99 mm. The height of the crimp section is 4.33 mm (4.33% D).

The total height of the concave inlet and convex crimp sections of the matrix is 18.13 mm (18% D).

The conjugation point of the input and crimp sections is determined from the equality of the derivatives of the parabola and the ellipse and has the coordinates x ₂ = -1.21, y ₂ = 4.33 mm. The diameter of the circle at the interface between the input and crimp sections d _c = 32.5 mm The angle of inclination of the tangent to both curves to the plane of the cross section of the matrix at the conjugation point is 12 °, and the angle of inclination of the tangent to the parabola at point B is 33 °.

In the general X-Y coordinate system, tied to the matrix bases:

X = x ₁ ; Y = y ₁ -y _1B ; _1B = 15.69;

X = x ₂ - (d / 2 + a); Y = y ₂ - (y _2C + y _1B -y _1C ); y _2C + y _1B -y _1C = 4.33 + 13.8 = 18.13;

в пределах от точки С (16,28, -13,8) до точки А (12,5, -18,13).The second-order working surface of the matrix is formed by the rotation of the parabola and ellipse sections and is described in the general coordinate system by the parabola equations Y = X ² / 152.8-15.69 in the range from point B (48.98, 0) to point C (16 , 28, -13.8) and then the ellipse

ranging from point C (16.28, -13.8) to point A (12.5, -18.13).

The surface quality of the bar is high.

Example 2. Pressing a d75 mm bar from an alloy CAC-1-50 from a container D120 mm with a draw ratio of 2.56.

When forming the working surface of the matrix, the real self-organizing boundary of the stagnant zone was taken into account when pressing the SAS-1-50 alloy at a low speed through a flat matrix in the presence of a front washer made of plastic metal in front of the pressed workpiece. The working surface is adjusted due to distortions of the real self-organizing boundary (Fig. 2).

The input portion of the matrix is described by rotation around the matrix axis of the hyperbola portion of ₁ ^{2 /} b ² -x ₁ ² / a ² = 1. The hyperbole equation is calculated using the MathLab program using real points at the input section of the self-organizing boundary of the stagnant zone and the pressed metal. The distance between the imaginary (2a) and real (2b) vertices of the hyperbola is equal to 20.2 and 34 mm, respectively. The height of the inlet section is 10.7 mm (9% D).

The crimp section of the matrix is formed by rotation around the axis of the matrix of a circle y ₂ ² = R ² -x ₂ ² . The center of the circle lies on a straight line perpendicular to the axis of the matrix passing through the beginning of the calibrating girdle. The radius of the circle is R = 8 mm. The height of the crimp section is 7.3 mm (6% D).

The total height of the concave inlet and convex crimp sections of the matrix is 18 mm (15% D).

The angle of inclination of the tangent to the hyperbole and the circle to the plane of the cross section of the matrix at the conjugation point is 15 °, the angle of inclination of the tangent at the beginning of the input section β is 62 °, and the diameter of the circle at the conjugation point is d _c = d + 0.2 × (Dd) = 84 mm

в пределах от точки В (59.5, 0) до точки С (42; -10,7) и далее окружности

в пределах от точки С (42; -13,6) до точки А (37.5; -18).The working surface of the matrix is a second-order surface formed by the rotation of sections of the hyperbola and the circle, and is described in the general coordinate system by the equations of the hyperbola

ranging from point B (59.5, 0) to point C (42; -10.7) and then the circle

ranging from point C (42; -13.6) to point A (37.5; -18).

The surface quality of the bar is high.

Example 3. Pressing a bar d18 mm from the alloy САС-1-50 from a container D75 mm with a drawing coefficient ≈17.4.

Three-dimensional curved working surface of the matrix is formed according to the claims (Fig. 3).

Initial conditions for constructing the working surface of the matrix:

- the input portion of the matrix is formed by rotation around the matrix axis of the ellipse section 1 x ₁ ² / a ² + y ₁ ² / b ² = l, the major axis of which is perpendicular to the axis of the matrix and extends 10.6 mm above the upper plane of the matrix, the small axis is parallel to the axis matrices, parameters a and b of the ellipse and the offset of the minor axis relative to the axis of the matrix c are selected, respectively, 38.4, 23.2 and 2.8 mm, based on the conditions for ensuring the required depth of the input section and the angle of inclination of the tangent to the plane of the cross section of the matrix, the intersection point of the ellipse 1 with the upper plane of the matrix (point B) s an X coordinate = 34,5 (D / 2-1) mm, and the equation of the ellipse 1, converted to the base matrix has the form

- the crimped portion of the matrix is formed by rotation around the matrix axis of the portion of the ellipse 2 x ₂ ² / a ² + y ₂ ² / b ² = 1, the small axis of which is perpendicular to the axis of the matrix, the large axis is parallel to the axis of the matrix, the vertex of the minor axis of ellipse 2 coincides with the beginning of the gauge the belt (point A) with the coordinate X = 9 mm, the parameters a and b of the ellipse are 11 and 18.95 mm, respectively, based on the conditions for ensuring the necessary depth of the input section, and the equation of ellipse 1 reduced to the matrix base has the form

The second-order working surface of the matrix, formed by the rotation of the sections of the ellipse 1 and ellipse 2, was constructed using the standard Autodesk program, and the coordinates of the ellipse mating point in the general coordinate system X _C = 18.3, Y _C = -10.6 mm, and the angle of inclination of the common tangent to the ellipses 1 and 2 is 13 °. The total height of the concave inlet and convex crimp sections of the matrix is 29.3 mm (39% D).

The surface quality of the bar is high.

Example 4. Pressing a bar 7 d70 mm from the alloy САС-1-50 from a container D100 mm with a drawing coefficient ≈2.

The three-dimensional curved working surface of the matrix is close to the real self-organizing boundary of the stagnant zone when pressing the SAS-1-50 alloy at a low speed through a flat matrix in the presence of a front washer made of plastic metal in front of the pressed workpiece (Fig. 4).

With sufficient approximation, the input section of the matrix is described by the rotation around the matrix axis of a straight line segment Y = kX + b passing through point B, having an abscissa X = 49 mm in the case of blunting 1 mm, and an angle of inclination of 40 ° to the plane of the matrix cross section.

The crimp section of the matrix, as in example 2, is formed by rotating around the matrix axis a section of the circle y ₂ ² = R ² -x ₂ ^{2 with a} radius of 6 mm, centered on a straight line perpendicular to the axis of the matrix passing through the beginning of the calibrating girdle (point A with coordinate X _A = 35 mm).

A simple calculation allows you to determine the height of the crimp section of 4.6 mm (4.6% D), the input section of 9.95 mm (≈0.1 D) and the coordinates of the interface point of the input and crimp sections: X _C = 37.14, Y _C = -9.95 mm. The total height of the inlet and crimp sections will be 14.55 mm (≈15% D).

в пределах от точки С (37,14, -9,95) до точки А (35, -14,55).The working surface of the second-order matrix is described in the general coordinate system by the equations of the straight line Y = 0.84X-41.1, ranging from point B (49; 0) to point C (37.14, -9.95) and then circles

ranging from point C (37.14, -9.95) to point A (35, -14.55).

The surface quality of the bar is satisfactory.

If the ratios are not observed, tears were observed on the surface of the rods (Fig. 5) or undulation (Fig. 6).

Thus, the technical result of the proposed is to improve the surface quality of the press products of insufficiently plastic under the conditions of the thermodynamic cycle of pressing aluminum alloys, including eutectic and hypereutectic silumins, as well as increasing the manufacturability of pressing by reducing waste.

Claims (5)

1. The pressing matrix with a three-dimensional curved working surface, including the input section, conjugated with a convex crimp section, smoothly passing into the calibrating girdle, characterized in that the profile of the crimp section of the matrix is made in the form of a second-order surface formed by rotation around the axis of the matrix of the curve consisting of sections of a circle, ellipse, parabola, hyperbola or polynomial of the 2nd order, the height of the concave input section is 5-20% of the outer diameter of the matrix D, the height of the convex crimp section is t 3.5-35% of the outer diameter of the matrix D, the total height of the inlet and crimp sections is 15-55% of the outer diameter of the matrix D, the circle diameter at the interface between the inlet and crimp sections d _c is determined by the ratio d _c = d + (0, l + 0.6) × (Dd), where d is the diameter of the calibrating girdle. 2. The matrix according to claim 1, characterized in that the profile of the input section of the matrix is made in the form of a second-order surface formed by rotation around a matrix axis of a curve consisting of sections of a circle, ellipse, parabola, hyperbola or second-order polynomial. 3. The matrix according to claim 2, characterized in that the angles of inclination of the tangent to the curves forming the working surface at the beginning of the inlet portion and at the interface between the inlet and crimp sections to the plane of the cross section of the press product are respectively from 20 ° to 75 ° and from 0.5 to 60 °. 4. The matrix according to claim 1, characterized in that the profile of the input section of the matrix is the surface of a truncated cone. 5. The matrix according to claim 4, characterized in that the angle of inclination of the generatrix of the cone is equal to the angle of inclination of the tangent to the curve forming the working surface of the crimp section to the plane of the cross section of the press product at the interface with the input section and ranges from 20 ° to 60 °.

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