RU2110344C1 - Ingot extrusion method - Google Patents

Abstract

FIELD: plastic metal working, namely extruding ingots, mainly with lengthwise laminarity. SUBSTANCE: method comprises steps of assembling ingots by placing one blank inside another, making outer blank of more ductile material than another, mutually fixing blanks, heating ingot, placing it onto needle and extruding through cone die due to arranging it in container and applying axial compression effort to its end. Ingot is assembled at simultaneously forming on its outer surface annular protrusions, arranging assembled blanks in fitting provided with annular recesses and applying compression effort to ends of outer blank. Said annular recesses of fitting are filled by material of outer blank. Then said blanks are mutually fixed by moving initially inner blank relative to outer one at shaping slope at side opposite relative to effort applying side. The blanks are moved together relative to said annular protrusions. When ingot is placed onto needle said slope is arranged at side of cone die. EFFECT: enhanced efficiency. 9 dwg

Description

 The invention relates to the processing of metals by pressure, in particular to methods of pressing composite ingots with a thickness in order to obtain pipes with an external clad surface.

 Clad pipes, including those made of aluminum alloys, are used in the petrochemical, oil, and other industries. However, the production of high-quality clad pipes by hot deformation is associated with the need to preserve the physicomechanical properties of each metal and their strong bond.

 A known method of pressing composite in thickness of the ingots obtained by crystallization of the clad metal relative to the side surface of the workpiece from the clad metal in a semi-continuous casting process in which the ingot is heated, placed on a needle, installed in a container and applied axial compressive force to its end [1].

The disadvantages of this method include
the possibility of defects such as bubbles, captives, etc., on the contact surface of the cladding material is a cladable material, which in the presence of atmospheric air significantly affects the quality of the pressed products;
the use of special molds, since relatively small lengths of cladding material are used;
increased cost of clad pipes due to the need for machining the outer surface of composite ingots.

 There is also known a method of pressing ingots mainly with longitudinal layering, including assembling the ingot by placing one workpiece inside another, the external workpiece being made of more plastic material, fixing the workpieces together, heating the ingot, installing it on a needle, followed by pressing through a conical matrix by placing it in the container and the application to the end face of the axial compressive force [2] (prototype).

The known method is characterized by the following disadvantages:
possible weldability of the processed materials due to the presence of air at the border of the cladding material - cladding material;
the large thickness variation of the cladding material along the length of the pipe due to the lack of preliminary welding of the processed materials before their joint deformation;
a relatively low yield coefficient, because there is a need to separate a large length of the output end of the pipe.

 The objective of the invention is to develop such a method of pressing composite ingots, which would provide the required quality of clad pipes (minimum thickness of the cladding layer along the perimeter of the pipe, as well as along its length, high-quality welding of the processed materials, increased corrosion properties of the pipes, etc.) at high suitable output.

 The technical result is achieved by the fact that in the method of pressing ingots, mainly with longitudinal lamination, including assembling the ingot by placing one workpiece inside another, the external workpiece being made of more plastic material, fixing the workpieces together, heating the ingot, installing it on a needle, followed by pressing through the conical matrix by placing it in the container and applying axial compressive force to the end face, the ingot is assembled with the simultaneous formation of an external the surface of the annular protrusions by placing the assembled workpieces in a tooling having annular recesses and applying a compressive force to the ends of the external workpiece, the annular recesses of the tooling are filled with the material of the external workpiece, then the workpieces are mutually fixed by moving the original internal workpiece relative to the external workpiece with the formation of a step from the side opposite to the applied force, then the joint movement of the workpieces relative to tionary annular projections, and when a billet placed on the needle ledge with the tapered sides of the matrix.

 The implementation of the method of pressing composite ingots with thickness allows us to provide the required quality of clad pipes (both geometric dimensions, as well as the quality of welding of clad and clad materials) with a high yield coefficient.

 This is explained by the fact that the welding parameters of the processed materials, namely, the radial pressure value and the exposure time of the materials being welded at a given pressure value under the conditions of choosing a rational temperature-speed deformation interval, make it possible to ensure high-quality welding of the processed materials in the container before their joint deformation. Moreover, controllability of the technological parameters of the process of pressing composite ingots is achieved by choosing the optimal length of the workpiece from a more durable material and its excess over the length of the workpiece from the cladding material. As a result, the initial application of a deforming force only to a workpiece of a more durable material determines the process of obtaining a pipe by pressing from a monometall. During this pressing stage, the cladding material is firmly welded to the outer surface of the workpiece from a more durable material. In addition, such sequential pressing: monometallic pipe - clad pipe eliminates any possibility of moving the workpiece from the cladding material relative to the workpiece from a more durable material. The increase in yield is guaranteed by the longer length of the pressed pipe at standard lengths cut off from the outlet and the weighted ends of the pipe.

 Figure 1 shows the initial position of the tooling and workpieces before assembling the latter; in FIG. 2 - the stage of formation of annular protrusions on the external workpiece in the process of assembly of the workpieces; figure 3 - the initial position of the tooling and workpieces before their mutual fixation; in FIG. 4 - the final stage of mutual fixation of the blanks; in FIG. 5 - the initial position of the tooling and the fixed workpieces before performing operations to move them relative to the annular protrusions of the external workpiece; in FIG. 6 - composite ingot; in FIG. 7 - the initial position of the ingot in the container before performing the pressing operation; in FIG. 8 - stage of pressing the composite ingot; in FIG. 9 - pressed pipe.

 An embodiment of the proposed method for pressing ingots is as follows.

Pre-assemble the composite ingot (figure 1). To do this, in a thick-walled clip 1, for example, of hardened steel U8A, a matrix 2 is detachable in a vertical plane, also, for example, of hardened steel U8A, and having internal annular recesses, to fit the movement. (figure 1). Next, install in the hole of the matrix 2 with a minimum clearance of the workpiece 3 from a plastic material, for example, an alloy of aluminum with zinc grade AcPl. The geometric dimensions of the workpiece 3: length l ₁ , outer diameter D ₁ , inner diameter d ₁ . In the opening of the workpiece 3, the workpiece 4 is installed with a minimum clearance, for example, of aluminum alloy AMG-3. The geometric dimensions of the workpiece 4: length l ₂ ; inner diameter d ₂ ; the outer diameter D ₂ made with a minimum clearance with respect to the inner diameter d _{1 of the} workpiece 1 (not shown conditionally). At the end of the workpiece 4, a sleeve punch 5 is placed. It should be emphasized that the contacting surfaces of the workpieces 3 and 4 undergo standard preliminary preparation in order to eliminate defects and any films, for example, oil films.

When exposed to a static force P on the end of the sleeve punch 5 cause axial plastic compression of the material of the workpiece 3 and, as a result, filling them with the free volumes of the annular recesses in the split matrix 2 (Fig. 2). In this case, the plastic flow of the workpiece 3 material is accompanied by some radial pressure P acting on the workpiece 4. As a result, there is an elastic deformation of the workpiece 4, which causes a decrease in its inner diameter to d $\genfrac{}{}{0ex}{}{\text{*}}{\text{2}}$ (figure 2).

Then carry out the mutual fixation of the workpieces 3 and 4 relative to each other. For this, a step punch 6 is installed in the opening of the workpiece 4, the larger step of which is made with a diameter d, and the smaller with a minimum clearance with respect to the hole with a diameter d $\genfrac{}{}{0ex}{}{\text{*}}{\text{2}}$ . Tooling with blanks is placed coaxially on the plate 7 having a hole with a diameter of d ₁ (figure 3). The application of the axial force P ₁ to the end face of the step punch 6 (Fig. 3) causes the workpiece 4 to move relative to the workpiece 3. As a result, under the radial pressure P, the material of the workpieces 3 and 4 undergoes a local shear deformation on the contact surface, which on the one hand allows removal air from microvolumes, and on the other hand determines the conditions for the formation of metal bonds along the contact surface between the workpieces 3 and 4. It must be emphasized that the presence of a small step on the punch 6 allows This increases the rigidity of the tooling and guarantees a uniform distribution of radial pressure along the length of the workpiece 3. Fixing of workpieces 3 and 4 takes place at the stage when their ends are placed in one horizontal plane (from the application of force P ₁ ). On the opposite side of the blanks 3 and 4, a step of length L is formed (Fig. 4).

Next, the punches 5 and 6 are replaced with a punche 8 having a flat end. The diameter of the punch 8 is made to fit the movement relative to the hole in the detachable matrix 2. The action of the force P on the end face of the punch 8 leads to the movement of the fixed blanks 3 and 4 relative to the annular protrusions. Since this movement is accompanied by a shear deformation of the material of the workpiece 3 at the location of the annular protrusions, the workpiece 4 is given an additional radial pressure Δp. . By further moving the punch 8, the composite ingot is removed from the tooling (Fig.6). As a result of partial unloading of the workpiece 4 on the contact surface of the workpieces 3 and 4, a radial pressure of P ^{3 is created} .

Then the ingot is heated, for which an induction furnace is used. It should be emphasized that the stress field of magnitude P ^* , as well as the heating temperature, intensify the formation of metal bonds for the processed materials along the surface of their contact. By the time the ingot finishes heating, due to the presence of a step on one of its ends, the temperature of the workpiece 4 at a length equal to the length of the workpiece 3 will correspond to the required one. On the length L, the temperature of the workpiece 4 will be somewhat lower. The ingot is mounted on a movable needle 9 (conventionally shown stationary on the drawing) on which a press washer 10 is preliminarily placed. We emphasize that the ledge of the ingot thus faces the opposite side of the press washer 10. Insert the needle 9 with the press washer 10 and a heated ingot into the container 11, where the conical matrix 12 is rigidly fixed (Fig. 7).

When exposed to a force P on the press washer 10, the step of unpressing the workpiece 4 and pressing the pipe from monometall is carried out (Fig. 8). Due to the fact that the initial temperature of the workpiece 4 material in the step region was slightly lower, the stage of pressing the monotube causes an increase in pressure in the container to the value (P ^* Δp), which leads to high-quality welding of the processed materials before the joint deformation begins. The time required for high-quality welding of the processed materials is determined by the deformation rate when pressing a pipe from a monometall. The pressed pipe (Fig. 9) after cutting it will be a certain length of monometall (workpiece material 4) and a given length of the clad pipe.

A pilot test of the developed method was carried out during the pressing of clad AcPl tubes of aluminum alloy AMg-Z. The blanks had the following geometric dimensions, mm:
from AMg-3
outer diameter D ₂ - 135
inner diameter d ₂ - 25
length l ₂ - 120
Atspl brand aluminum
outer diameter D ₁ - 145
inner diameter d ₁ - 135
length l ₁ - 90
The ingots were assembled on a PSU-250 hydraulic press with a force of 800 kn. To activate the processed materials along the contact surface and to remove air from the microvolumes, the workpiece from AMg-3 was moved relative to the workpiece from AcPl. The effort required in this case did not exceed 2 mn. The ingots were heated in an induction furnace to 370 ^o C. The pressing was carried out by the direct method with a moving needle through a conical matrix (taper angle 135 ^o ) with a hole diameter of 32.0 mm, on a horizontal hydraulic press, developing a maximum force of 16 mn. The diameter of the needle is 24.0 mm. 12 m of clad pipes were pressed with a cross section of (32 • 4) mm. Metallographic studies carried out on samples cut every 200 mm of the pipe length showed the thickness of the clad layer to be between 8-17%, which corresponds to the technical requirements for the production of these products. Corrosion tests revealed an increase in pipe corrosion resistance by at least 4 points.

 The invention can be used to obtain oil pipes, pipes for coal (mines) and food industry, etc.

Claims (1)

 A method of pressing ingots predominantly with longitudinal layering, including assembling an ingot by placing one workpiece inside another, the outer workpiece being made of a more plastic material, fixing the workpieces together, heating the ingot, installing it on a needle, followed by pressing through a conical matrix by placing it in a container and applications to the end face of the axial compressive force, characterized in that the ingot is assembled with the simultaneous formation of an annular protrusion on its outer surface by placing the assembled workpieces in a tooling having annular recesses, and applying a compressive force to the ends of the external workpiece, fill the annular recesses of the technological tooling with the material of the external workpiece, then mutually fix the workpieces by moving the original internal workpiece relative to the external one with the formation of a step with side opposite to the applied force, then perform the joint movement of the workpieces relative to the annular protrusions , and when installing the ingot on the needle, the ledge is placed on the side of the conical matrix.

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