RU2738630C1 - Composite workpiece for forging residue - Google Patents

Abstract

FIELD: metal forming.SUBSTANCE: invention relates to metal forming. Composite workpiece for forging draft is made in form of cylinder and enveloping it circular shell. Wall of shell has shape in form of isosceles triangle, base of which adjoins side surface of cylinder. In the vertex of the isosceles triangle, which is located in the middle of the height of the cylinder, the shell has maximum wall thickness. Height of the isosceles triangle is selected taking into account the diameter and height of the cylinder from the condition of obtaining, after the forging draft, the boundary between the annular shell and the deposited cylinder having the rectilinear generatrix.EFFECT: simplified separation of the workpiece from the shell.6 cl, 1 tbl, 11 dwg

Description

The proposed device relates to the field of metal forming, or rather to the configuration of blanks for forging metal.

The operation of forging upsetting is used for plastic deformation of workpieces in order to change their shape and / or increase the mechanical properties of the deformable material.

From the prior art, configurations of workpieces for forming are known, their shape often determines the improvement of the performance of the stages of subsequent deformation [1]. The composite billet for deformation may include a cladding or shell [2,3], which protects the base metal from oxidation or gas saturation when heated. The complex structure of the blank can predetermine the production of a composite as a final product [4,5].

A special group of blanks is made up of objects intended for forging upsetting performed on hammers or presses. The lateral surface of cylindrical blanks remains free from the action of compressive stresses, therefore, it can easily begin to fracture with the formation of cracks. Techniques have been repeatedly proposed by which the level of compressive stresses in processes similar to forge sludge could be increased [6,7].

In particular, there is a known method of placing a cylindrical blank into an annular shell. The annular shell creates a support for the plastic flow of the base metal, which makes it possible to increase the level of compressive stresses and thereby increase the plasticity of the metal. The use of this technique is implemented in the description of the invention [8]. In this case, the assembly of plastically deformable materials is a cylindrical blank and an annular shell covering the middle part of its lateral surface. Upsetting is carried out by applying a compression force to the ends of the workpiece with simultaneous stretching of the shell. The procedure includes three stages. At the first stage, upsetting is carried out until the degree of deformation is reached, which does not exceed the maximum permissible value when upsetting metal without a shell. At the second stage, the workpiece is placed in a shell and the assembly continues to be loaded in the area of plastic deformations. The presence of the shell allows you to do this without destroying the metal. At the third stage, a degree of deformation is reached at which the shell breaks. Thus, it is possible to remove the shell without the use of special operations.

From the last example, it is clear that there is a desire to create processing techniques that facilitate the removal of the shell. There are several options in the industry for its removal. The most common option is to remove the flank into chips on a lathe. The disadvantage is the need for partial removal of the material of the cylindrical workpiece itself due to the unevenness of the lateral surface arising during the forging draft, which is called barrel formation. In another embodiment, the shell is etched in solutions of alkalis and acids, selecting their compositions so that they affect the metal of the shell, but do not affect the metal of the cylindrical workpiece.

In the invention [9], as a method of removing the shell, it was proposed to manufacture the shell itself by winding a wire. After the upsetting operation, the wire could be removed by unwinding.

All these additional methods of removing the shell had to be developed due to the curvature of the lateral surface. If it did not exist, then it was possible to separate the workpiece and the shell by pressing the workpiece out of the shell. Therefore, the disadvantage of analogs is the impossibility of extruding the blank from the shell due to the curvature of the lateral surface.

The prototype described in the book [10] was identified by the greatest number of essential features. The prototype object is a composite blank for forging upsetting, consisting of a cylinder and enclosing it along the lateral surface of an annular shell having an inner diameter equal to the cylinder diameter.

The annular shell has a rectangular cross-section, with the larger base of the rectangle adjacent to the lateral surface of the cylinder. Thus, the wall thickness of the annular shell has the same height dimensions. During forging upsetting, the boundary between the workpiece and the shell becomes curved due to the action of friction forces. As a result, an attempt to extrude the cylinder from the shell leads to a negative result. The second disadvantage is the possibility of a gap formation between the surface of the cylinder and the inner surface of the shell. As a result, the backing effect from the shell side is lost.

The technical problem to be solved by the claimed object is to create the possibility of using a fairly simple method of dividing the workpiece into a cylinder and a shell in the form of extrusion of the cylinder and shell. Another technical problem to be solved by the claimed object is the stabilization of the cylinder diameter, that is, the elimination of the curvature of the boundary between the cylindrical workpiece and the shell, which makes it difficult to apply fairly simple methods of separating these objects after the forging upset operation.

A composite billet for forging upsetting is proposed, consisting of a cylinder and an annular shell enclosing it along the lateral surface of an annular shell, having an inner diameter equal to the cylinder diameter.

The workpiece is characterized in that the wall thickness of the annular shell has different heights, with the maximum wall thickness located in the middle of the cylinder height. The increase in wall thickness in the direction of the middle of the height of the cylinder is justified by the fact that during upsetting the greatest backwater is created precisely in the region of the middle of the height, which interferes with the process of barrel formation. As a result, instead of a convex outer surface of the cylinder, it is possible to obtain a sufficiently flat cylindrical surface after upsetting, and the shell can be separated from the cylinder by a simple extrusion operation. By mathematical modeling, the profile of the shell wall can be selected in such a way that it will create the necessary support, and for low-plastic alloys this support should be higher than for more plastic alloys. The shell profile in this case can be described by a curved generatrix.

However, the simplest form of the shell wall is an isosceles triangle. Therefore, the maximum wall thickness can be reached at the apex of an isosceles triangle that describes the wall profile of the annular shell, with the base of the triangle adjacent to the lateral surface of the cylinder. The triangular shape of the shell wall, in contrast to the curvilinear one, is preferable in that such a shell can be turned on the simplest turning equipment.

At the same time, the presence of a triangular wall suggests the appearance of ribs, including those with rather sharp angles, especially at the base of an isosceles triangle. To reduce the level of stress concentration, it is proposed to equip the edges of the annular shell with fillet radii. The presence of fillet radii allows avoiding stress concentration not only in the shell edges themselves, but also in the workpiece zones in contact with these edges. In addition, the presence of sharp edges does not allow creating a reliable support of the shell on the support ring when implementing the pressing-out technique. The radius of the bends allows you to create a reference pad instead of a point contact.

The geometric parameters of the wall of the annular shell are selected from the condition of maintaining the straightness of the generatrix of the cylinder. These parameters will depend on the friction conditions, compression mode, material properties. The possibility of such a selection will be proved below.

One of the materials requiring deformation processing is magnesium and magnesium-based alloys. This is due to the low ductility of the metal in the cold state. For the shells in this case, copper is often used as a material with an increased level of ductility, withstanding a high level of tensile stresses without necking. Therefore, it is proposed, in one of the variants, to make the cylinder of magnesium alloy, and the shell to be made of copper.

FIG. 1 shows a general diagram of the upsetting process of a preform with a shell according to the prototype before deformation, FIG. 2 the same after deformation with an idealized picture in the absence of friction. FIG. 3 shows a diagram of deformation and a longitudinal section of the workpiece and the shell according to the prototype after deformation under the action of friction and the formation of a curved boundary between the shell and the workpiece. FIG. 4 shows the relative position of the blank and the shell according to the proposed technical solution in the form of a shell with different heights of dimensions, with the maximum wall thickness located in the middle of the height of the cylinder. FIG. 5 shows the profile of the billet after upsetting while maintaining the straightness of the generatrix of the cylinder. FIG. 6 shows the profile of a composite blank where the shell has an isosceles triangle profile. FIG. 7 shows a diagram of extrusion of the cylinder from the shell in the presence of straightness of the generatrix of the cylinder. FIG. 8 shows a variant of the profile of the lateral surface of the cylinder after forging upsetting in the absence of a shell. FIG. 9 shows a variant of the profile of the lateral surface of the cylinder as part of a composite billet after forging upsetting in the presence of a shell, but with too much backing on its side (obtaining a concave surface). FIG. 10 shows a variant of the profile of the lateral surface of the cylinder as part of a composite billet after forging upsetting in the presence of a shell, but with too little backing on its side (obtaining a convex surface). FIG. 11 shows a variant of the profile of the lateral surface of the cylinder as part of a composite billet after forging upsetting in the presence of a shell with parameters according to the proposed technical solution.

The scheme of deformation by forging upset according to the prototype is shown in Fig. 1. It is shown here that the cylindrical blank 1 is placed in an annular shell 2 of rectangular cross-sectional shape. Such an assembly is placed between strikers 3 and 4 and is compressed in the direction of the arrows by the force of a press or hammer. If there was no friction on the surface of the tool, then after deformation the diameters of the workpiece and the shell increased (Fig. 2) while maintaining the straightness of the boundary between them. However, according to the prototype, due to the action of frictional stresses on the contact surface, the lateral surface of both the cylindrical blank and the shell acquires a curvilinear shape (Fig. 3). As a result, they cannot be separated by a simple pressing-out method.

According to the proposed solution, a composite billet for forging upset is proposed, which is a cylinder 1 (Fig. 4) and an annular shell 5 covering it along the lateral surface, having an inner diameter equal to the diameter of the cylinder. The wall thickness of the annular shell 5 has different height dimensions, with the maximum wall thickness being located in the middle of the cylinder height. This is achieved by using a curved generatrix for the outer surface of the shell. In the figure, the shell height is denoted as h _o , and the cylinder height as H _o . It can be seen here that the height h _{o is} less than the height of the cylinder, which is due to the fact that during the subsequent draft, the heights will not change equally.

FIG. 5 shows that with the correct selection of the geometrical parameters of the shell after upsetting to the height H _{1, the} boundary between the cylinder and the inner surface of the shell is described by a straight generatrix, which in the future allows the shell to be removed by pressing.

In a simpler version, the maximum wall thickness of the annular shell is achieved at the apex of the isosceles triangle, which describes the profile of the wall of the annular shell 6 (Fig. 6), while the base of the triangle adjoins the lateral surface of the cylinder, and the apex of the triangle and the vertices at its base form the edges of the annular shell ... As in the previous case, the height of the shell is denoted as h _o , and the height of the cylinder as H _o , but in this case h _o is the base of the isosceles triangle.

The scheme of the extrusion operation can include the use of support 7 (Fig. 7), on which the ring 8 is installed, and on it is placed a composite workpiece consisting of a cylinder 1 and a shell 5. The inner working diameter of the ring 8 is equal to the diameter of the cylinder 1. On the end of the cylinder 8 is installed firing pin. The force of the press (white arrow) pushes the cylinder 1 into the hole of the ring 8, while the shell remains stationary. This action can be performed if cylinder 1 has a straight generatrix.

To prove the achievement of the technical result, calculations by the finite element method were performed in the DEFORM software module for the settlement of a composite workpiece in several versions.

The formulation of the problem included a description of the deformation zone geometry in the initial state, a description of the physical and plastic properties based on reference data, and the setting of boundary conditions in displacements. The relative reduction is 50%.

The magnesium sample is presented in the form of a cylinder with a diameter D ₀ = 15 mm and a height H ₀ = 15 mm (H ₀ / D ₀ = 1), a diameter D ₀ = 7.5 mm and a height H ₀ = 15 mm (H ₀ / D ₀ = 2) and a diameter D ₀ = 30 mm and a height H ₀ = 15 mm (H ₀ / D ₀ = 0.5).

The Siebel friction index is 0.1.

FIG. 8 (parameter H ₀ / D ₀ = 1) shows a longitudinal section of the right half of cylinder 1 subjected to forge upsetting without a shell (a case typical for analogs). Hereinafter, the figures show the finite element mesh.

It can be seen here that due to the action of frictional forces at the interface with the tool, the lateral surface underwent bending. Calculations revealed that in the middle of the surface, the average normal stress turned out to be reduced in absolute value relative to the central zones of the cylinder. This can cause destruction of the peripheral metal layers.

Further, the calculations were carried out at variable values of the geometric parameters: the initial height of the shell h ₀ , the initial height of the isosceles triangle s ₀ , the initial height and diameter of the cylinder H ₀ and D ₀ . The dimensionless parameter s ₀ / D _{0 was} created from these dimensional quantities. As a function of this parameter, as a result of solving the problem, the dimensionless parameter D _b / D _{k was} obtained, where D _b is the largest diameter of the cylinder (along the barrel), D _k is the smallest diameter of the cylinder (along the contact surface). At D _b / D _k , <1, a concave lateral surface of the cylinder was obtained, at D _b / D _k > 1, a convex lateral surface was obtained. Obtaining the value D _b / D _k , = 1.00 meant the achievement of the technical result - obtaining the shape of the surface with a generatrix in the form of a straight line. These results are shown in the table.

Table

Shaping the cylinder in the presence of a shell

No. Sheath dimensions, mm H ₀ / D ₀ s ₀ / D ₀ D _b / D _k h ₀ s ₀ one 7 0.3 0.5 0.01 1.03 2 0.5 0.016 1.01 3 0.7 0.023 1.01 4 1.0 0.033 1.01 5 1.5 0.05 1.00 6 2.0 0.066 1.00 7 2.5 0.083 1.00 8 3.0 0.1 0.99 nine 3.5 0.116 0.99 ten 4.0 0.133 0.99 eleven 7 0.3 one 0.02 1.03 12 0.5 0.033 1.00 13 0.7 0.046 1.00 14 1.0 0.066 1.00 15 1.5 0.1 0.98 16 2.0 0.133 0.98 17 2.5 0.166 0.97 eighteen 3.0 0.2 0.97 19 3.5 0.233 0.96 twenty 4.0 0.266 0.96 21 7 0.1 2.0 0.013 1.01 22 0.15 0.02 1.00 23 0.2 0.027 1.00 24 0.3 0.04 0.99 25 0.5 0.067 0.96 26 0.7 0.093 0.94 27 1.0 0.133 0.92 28 1.5 0.2 0.88 29 2.0 0.267 0.88 thirty 2.5 0.333 0.87 31 3.0 0,4 0.87 32 3.5 0.467 0.86

It can be seen from the table that for H ₀ / D ₀ = 0.5, the value of D _b / D _k , = 1.00 is achieved when the inequality 0.050 <s ₀ / D ₀ <0.083 is fulfilled, that is, such a range of initial geometric parameters allows solving the technical the problem of stabilizing the cylinder diameter after the upsetting process. Accordingly, for H ₀ / D ₀ = 1, the value of D _b / D _k , = 1.00 is achieved in the range 0.033 <s ₀ / D ₀ <0.066, and for H ₀ / D ₀ = 2.0 at 0.020 <s ₀ / D ₀ <0.027.

Thus, it is shown here that for the range 0.5 <H ₀ / D ₀ <2.00, at which the forging upset is usually carried out, it is possible to find such a ratio s ₀ / D ₀ in which the lateral wall of the cylinder is described by a straight generatrix.

FIG. 9 shows a longitudinal section of the right half of a composite billet with a cylinder parameter 1 equal to H ₀ / D ₀ = 1, subjected to forge upsetting with a shell 2 with a too thick wall. It can be seen here that the generatrix of the cylinder has received a too strong curvature and has acquired a concave shape. FIG. 10 shows a longitudinal section of the right half of a composite blank with the same ratio H ₀ / D ₀ , subjected to forge upsetting with a shell 2 with too thin a wall. It can be seen here that the generatrix of cylinder 1 has received too much curvature and has acquired a convex shape. FIG. 11 shows that it is possible to obtain a generatrix of the cylinder 1 close to a straight line (parameter H ₀ / D ₀ = 1), deposited in the shell 2, which proves the possibility of implementing the technical solution.

For the given examples, the edges of the annular shell have radii of rounding equal to 0.1 mm.

The technical result consists in solving the technical problem posed: creating the possibility of using a fairly simple method of dividing the workpiece into a cylinder and a shell in the form of extrusion of the cylinder and the shell. This problem is solved simultaneously with solving another problem of stabilizing the diameter of the cylinder, that is, eliminating the curvature of the boundary between the cylindrical workpiece and the shell, which makes it difficult to apply fairly simple methods of separating these objects after the forging upsetting operation. If at the end of the technological cycle it is required to obtain the correct cylinder, then obtaining such a shape already at the stage of forging upsetting reduces metal waste in the form of chips during the lateral surface turning operation.

Information sources

1. Patent for utility model RU 170655. Blank for rolling of round section profile / Loginov Yu.N., Postylyakov A.Yu., Inatovich Yu.V. IPC B21B 1/16. Application 2016108073 dated 03/04/2016. Publ. 05/03/2017. Bul. No. 13.

2. A.c. SU 1358231. Blank for the manufacture of clad sheets by rolling and the method of rolling clad sheets / VK Korol, EA Polyakov, VI Popov. and other Application 853980856 from 20.11.1985. IPC B23K 20/00.

3. Patent for invention RU 2220850. Composite billet for hot deformation / Tetyukhin VV, Altman PS, Polyansky SN et al. IPC B32B 15/00. Application 2002103559 dated 02/08/2002. Publ. 10.01.2003. Bul. No. 1.

4. Patent US8980439. Bimetallic forging and method / Carlson Blair, Krajewski Paul. IPC B21J 5/02, B32B15 / 01. Application US2012088116 from 2012-04-12. Publ. 2015-03-17.

5. Patent for utility model RU 178157. Multilayer billet for hot rolling / Kramer A.A. Application 2016126384 dated 06/30/2016. IPC B23K 20/00, B32B 15/01. Publ. 26.03.2018. Bul. No. 9.

6. Kamenetsky BI, Loginov Yu.N., Kruglikov N.A. Influence of lateral backwater conditions on the plasticity of magnesium during cold draft. Light alloy technology. 2012. No. 1. S. 86-92.

7. Kamenetsky BI, Loginov Yu.N., Volkov A.Yu. Methods and devices for increasing the ductility of brittle materials during cold settlement with lateral support. Blank production in mechanical engineering. 2013. No. 9. S. 15-22.

8.A.S. SU 1759512. Method of upsetting cylindrical billets from low-plastic materials / Loginov Yu.N .. IPC B21J 1/04. Application 4896490 dated 26.12.1990. Publ. 09/07/1992. Bul. No. 33.

9.A.S. SU 1007803. Method of upsetting blanks / Loginov Yu.N., Khaikin BE. IPC B21J 5/00. Application 3242034 dated 02.02.1981. Publ. 03/30/1983. Bul. No. 12.

10. The mighty L.N. Pressure treatment of hard-to-form materials. Moscow: Mashinostroenie, 1976.272 p.

Claims (6)

1. Composite blank for forging upset, made in the form of a cylinder and encompassing it along the lateral surface of the annular shell, the inner diameter of which is equal to the diameter of the cylinder, characterized in that the annular shell is made with a wall profile in the form of an isosceles triangle, the base of which adjoins the lateral surface of the cylinder , while at the apex of the isosceles triangle, which is located in the middle of the height of the cylinder, the annular shell has the maximum wall thickness, and the height of the isosceles triangle s _{0 is} selected taking into account the diameter D ₀ and the height of the cylinder H ₀ from the condition of obtaining the boundary between the annular shell and upset cylinder having a straight generatrix. 2. A workpiece according to claim 1, characterized in that when H ₀ / D ₀ = 0.5, the height of the isosceles triangle s _{0 is} selected from the range 0.050 <s ₀ / D ₀ <0.083. 3. A workpiece according to claim 1, characterized in that when H ₀ / D ₀ = 1, the height of the isosceles triangle s _{0 is} selected from the range 0.033 <s ₀ / D ₀ <0.066. 4. A workpiece according to claim 1, characterized in that when H ₀ / D ₀ = 2, the height of the isosceles triangle s _{0 is} selected from the range 0.020 <s ₀ / D ₀ <0.027. 5. Blank according to any one of paragraphs. 1-4, characterized in that the edges of the annular shell, formed by the vertices of the isosceles triangle, are rounded along the radius. 6. Blank according to any one of paragraphs. 1-5, characterized in that the cylinder is made of magnesium alloy, and the shell is made of copper.

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