RU2514531C2 - MAKING AXIALLY SYMMETRIC FORGED BLANKS OF BARREL- AND BOWL-TYPE FROM HIGH-STRENGTH ALUMINIUM ALLOY OF Al-Zn-Mg-Cu-SYSTEM ALLOYED WITH SCANDIUM AND ZIRCONIUM - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming and can be used for making the axially symmetric forged blanks of barrel- and bowl-type from high-strength aluminium alloy of Al-Zn-Mg-Cu-system alloyed with scandium and zirconium. Heated cast cylindrical blank is placed in female die and formed by male die in two steps. At first step, said blank is upset. At second step article walls with preset profile and bottom are formed. Both steps are performed in one job by local application of load. Outer surface of article bottom is formed by male die located at angle of 5 degrees to female die axis. Male die is rotated at 200 rpm. Wall and bottom inner surface is formed by female die with extractor at their rotation at speed equal to that of male die. Female die is displaced towards the male die at speed varying at the rate of 15 to 1 mm/s.

EFFECT: higher metal recovery and quality of produced articles.

2 cl, 2 dwg, 2 tbl, 1 ex

Description

The invention relates to the processing of metals by pressure and can be used in the forge shops of metallurgical and engineering plants in the manufacture of axisymmetric stamped blanks such as glasses and bowls with a ratio of height to outer diameter H / D = 0.15-0.35 and wall thickness to outer diameter S / D = 0.05-0.1 with a complex contour bottom having thickenings of various shapes and sizes. These semi-finished products are intended for the manufacture of centrifuge covers, diaphragms, plugs, blind bushings and other similar products for nuclear energy, chemical engineering, and the oil and gas processing complex.

A known method of manufacturing hot stamping on a hydraulic press of glass-type parts, including the reverse extrusion of a cylindrical workpiece through an axisymmetric channel formed by the surfaces of the matrix and punch according to the patent: Belgium, No. 551053, class. B21C 25/08, publ. 1956.

The disadvantages of this method are:

1. The need to use powerful, energy-intensive equipment - a hydraulic press;

2. Low CMM stampings (within 0.2-0.4) due to large inlets, stamping slopes and allowances;

3. The low quality of the stamping material — heterogeneity of the macrostructure, low level and large dispersion of mechanical properties due to poor deformation study of the original cast billet.

There is also known a method of extruding hollow parts (including type of glasses) on a specialized installation according to the patent of the Russian Federation No. 2254202, B21K 21/00, publ. 06/20/2005, adopted as a prototype. The method includes plastic deformation of the metal during rotational and translational motion from independent drives of one of the deforming tools — a matrix moving towards the stationary punch, while the rotational speed is much higher than the translational speed. Both deforming tools are located on the same vertical axis.

This method can significantly reduce the deformation force and, therefore, use less energy-intensive equipment, due to the possibility of regulating the ratio of the translational and rotational speeds of the matrix, necessary in the manufacture of axisymmetric parts of various configurations, sizes and materials. The ratio of the speeds of translational and rotational movement of the tool (i = v / n, where v is the speed of translational movement, mm / s; n is the speed of rotational movement, 1 / s) is taken as a constant value for a particular stamping, not exceeding 2.5. This method allows the use of less powerful equipment, however, it has inherent disadvantages such as low CMM stampings, heterogeneity of the structure and a large dispersion of mechanical properties in the finished product.

The present invention solves the problem of improving the stamping technology of these products in relation to the high-strength aluminum alloy of the Al-Zn-Mg-Cu system alloyed with scandium and zirconium.

The technical essence of the proposed method of hot stamping on specialized equipment is that a cast cylindrical billet installed in the lower part of the stamp (a rotating die with an ejector) is also deformed by a punch rotated at the same speed and inclined at an angle of 5 ^° to the vertical axis of the die. The matrix in the process of deformation moves vertically upward towards the punch with a regulated speed of 15 mm / s to 1 mm / s. These factors create the necessary variable, a gradually increasing level of localization of the deformation zone during the stamping process. Stamping is carried out in one step in two stages, including upsetting and subsequent molding of the product, while the product wall and the inner surface of its bottom are formed by a die with an ejector, and the outer surface of its bottom is formed by the aforementioned punch.

Figure 1 shows a diagram of the implementation of the proposed method.

The method is carried out in the following way. Before supplying the workpiece to the working surfaces of the deforming tool, technological lubricant is applied. Heated to a temperature of 400 ° C, a cast cylindrical billet 1 with a height not exceeding 1.7 diameters is installed in the lower part of the stamp — a matrix consisting of a body 2 and inserts 3 and 4. The matrix body is fixedly mounted on a movable platform 5. The workpiece is usually based on on the ejector 6 located inside the matrix due to the groove made on the end face of the workpiece (not shown in the drawing). After turning on the equipment, the rotational movement of the deforming tool begins at a speed of 200 rpm. Due to the vertical movement of the rotating matrix and the ejector located in it, the initial contact of the workpiece with the punch 7 rotating at the same speed, inclined at a 5 ° angle to the vertical axis of the matrix by the punch holder 8. After contact is established, plastic deformation of the workpiece begins, including the steps of settlement with a deformation rate inversely proportional to the current variable area of the workpiece until the workpiece touches the matrix wall and subsequent molding adannogo slozhnokonturnogo bottom profile and wall products carried by the topical application of the load with a monotonically increasing level of localization within the value λ = Fk / F from 0.5 to 0.08 (where λ - relative contact area; Fk - current contact area mm ² ; F - total current area of the workpiece, mm ² ). In this case, the outer surface of the bottom of the product is formed by the aforementioned punch, and all other surfaces are formed by a matrix and an ejector. The matrix with the ejector moves during the deformation in the vertical direction upwards with an adjustable variable speed from 15 mm / s at the beginning of deformation to 1 mm / s at the end of the process. The specified parameter is selected based on the conditions of maximum process performance at the upsetting stage and better design of the complex contour of the part at the final stage of shaping. Specific values of the parameter, depending on the shape and size of the product, are indicated in terms of the change in speed, compiled before the start of deformation. The plan for changing the speed during the stamping process is performed automatically by the equipment. The force is formed depending on the contact area and the resistance of the material to deformation. The rotation of the tool, the vertical movement of the matrix with the ejector with the specified speed and the inclination angle of the punch provide the necessary localization of the deformation and its intensity. After the deformation process is completed, the matrix with the ejector and with stamping is moved down, and the finished product is removed from the matrix using the ejector.

The proposed method for the manufacture of axisymmetric glasses or bowls differs from the prototype in that:

- the figured punch is located at an angle of 5 ° to the vertical axis of the matrix and rotates around its own axis with an angular velocity equal to the speed of rotation of the matrix;

- the punch and die have their own synchronized rotation drives;

- the speed of movement of the rotating matrix in the vertical direction up is an adjustable value that varies during deformation from the maximum value at the stage of precipitation to the minimum value at the stage of molding.

The technical result is to increase the CMM stamping to 0.7-0.75 and improving the quality of the stamping material.

The proposed method has the following advantages:

- allows you to use less energy-intensive deforming equipment due to a significant reduction in the deformation force associated with the localization of the deformation zone. Typically, the force is reduced by 8-10 times compared with traditional extrusion stamping without rotating the tool;

- allows you to increase the CMM of stampings due to obtaining a significant surface area of the product, which does not require machining and reduce by 50% the allowances for machining of the remaining surfaces;

- allows you to increase the strength, plastic and resource properties of the stamping material due to the impact of intense plastic deformation, providing a deep deformation study of the structure associated with crushing and grinding of excess phases, as well as the formation in the finished product of a homogeneous, fine-grained, fibrous structure that repeats the contour of the product.

Examples of the method.

By the proposed method, several batches of stamped blanks were made from high-strength aluminum alloy of the Al-Zn-Mg-Cu system alloyed with scandium and zirconium. The geometric shape and dimensions of typical stampings are shown in figure 2 (a, b, c).

All stampings were made of cast billets of ⌀65 mm, lengths of 95, 90 and 85 mm, respectively. In the manufacture of stamping (a), a plan was set for changing the speed of vertical movement of the matrix during the deformation process, shown in table 1.

Table 1  Plan for changing the speed of vertical movement of the matrix depending on the height of the workpiece The current height of the workpiece, mm The speed of vertical movement, mm / sec 95 fifteen 75 10 55 7 40 four 25 2 17 -

The outer bottom surface of all stampings does not require machining. The allowances for machining the remaining surfaces are reduced by 50%. As a result, KIM stampings ranged from 0.7 to 0.75.

The test results of heat-treated stampings made by the known and proposed methods are shown in table 2.

table 2  The mechanical properties of stamping (a) from an alloy of the Al-Zn-Mg-Cu system alloyed with scandium and zirconium in a heat-treated state made according to the known and proposed methods A method of manufacturing a stamping Sample cutting direction σ _in , MPa σ _0.2 MPa δ,% KCU, J / cm ² Famous Chord 650 608 2.1 4.0 Radial 627 582 2.0 5,0 Proposed Chord 684 643 5.2 9.0 Radial 686 650 5,4 10.0

From the analysis of the table it follows that the stamping (a) obtained by the proposed method has higher strength characteristics, and the plastic properties (δ, KCU) are two times higher than the corresponding properties of the stamping obtained by the known method.

Studies of the microstructure of stampings obtained by the known and proposed methods showed that particles of excess phases of crystallization origin in the stamping obtained by the proposed method are much more dispersed (4-5 times), their size spread is an order of magnitude smaller, and their distribution over the aluminum matrix more uniform. In addition, the stamping structure in both cases is not recrystallized (polygonized), but in the stamping obtained by the proposed method, the subgrains are smaller. These structural differences are explained by the fact that upon receipt of the product by the proposed method, the excess phases are crushed and evenly distributed over the volume of the aluminum matrix.

Based on the actual data presented in table 2, we can expect a significant increase in the resource of the finished part.

The stamping force was from 0.38 MN (38 tf) for stamping (c) to 0.4 MN (40 tf) for stamping (a) and (b).

The force for stamping these products by a known method of extrusion on a hydraulic press without rotation, calculated by the formula given in the Handbook of the blacksmith-puncher edited by V.L. Raskind (M., Higher School, 1985, P. 220) amounted to 3.8 MN (380 tf).

P = K _D · F · σ _bt , where P is the design force required for stamping, MN;

F is the stamping area in plan, m ² ; σ _bt is the tensile strength of the material at the temperature of stamping termination equal to 22 MPa.

For stampings round in the plan K _D = 8 · (1-0,001D) · [1,1+ (20 / D)] ² ,

where D is the diameter of the round forgings in terms of 145 mm.

F = 3,14 · D ^2/4 = 16505 mm ² m ² ≅0,0165

K _D = 8 · (1-0.001 · 145) · [1.1+ (20/145)] ² = 10.48

P = 10.4810.0165.22 = 3.8 MH, (380 tf)

Thus, the force during stamping of the proposed method is approximately 10 times less than in the manufacture of these parts by a known extrusion method without rotating the tool.

Claims (2)

 1. A method of manufacturing stamping axisymmetric products such as glasses and bowls from high-strength aluminum alloy of the Al-Zn-Mg-Cu system alloyed with scandium and zirconium, made with the ratio of the height H and wall thickness S to the outer diameter D N / D = 0.15- 0.35, S / D = 0.05-0.1, having a complex contour bottom and thickenings of various shapes and sizes, characterized in that the heated cast cylindrical billet is installed in the lower part of the stamp in the form of a matrix with an ejector and its plastic deformation is performed by a punch in two stages, on one and from which they carry out the draft of the workpiece, and then form the walls of the product with a given profile and bottom, both stages of plastic deformation being carried out in one operation by local application of load with a change in the shape of the workpiece by providing its intense high-speed plastic deformation with a variable, gradually increasing level of localization, while the outer surface of the bottom of the product is formed by the said punch located at an angle of 5 ° to the vertical axis of the matrix, when it rotates with a constant at a speed of 200 rpm, and the wall and the inner surface of the bottom of the product are formed by means of a matrix with an ejector during their rotation at a speed equal to the speed of rotation of the punch, and moving in the vertical direction towards the punch with a speed that varies during deformation from 15 to 1 mm / s 2. The method according to claim 1, characterized in that the punch and the die are rotated by means of their own synchronized rotation drives.

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