RU2478013C1 - Method of producing bar blank - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to making metal bar blank to be used for further conversion. Proposed method comprises placing preheated bar blank in press container, process metal washer and press washer, blank premoulding and molding. Bar blank diameter equal that of process washer. Prior to heating, bar blank rear end is shaped to truncated cone with vertex angle making (1.0-1.5) of conical female die angle. Recess with surface similar to that of blank contact surface is made on process washer surface in contact with blank surface. In particular version, blank bar rear end surface and that process washer in contact therewith have coat of substance to rule out contact welding in moulding. Note here that moulding is made so that, in forming moulding residue from process washer material, time of metal displacement from peripheral point die aperture to central point die aperture equal time of metal displacement to blank rear end central point die aperture.

EFFECT: ruled out metal peeling and moulding residues, higher yield.

3 cl, 1 tbl, 3 dwg

Description

The present invention relates to the processing of metals by pressure - pressing with a high yield of bar stock on horizontal and vertical presses, which can be used for the manufacture of fasteners. The method can significantly increase the yield, thereby ensuring the saving of expensive materials.

A known method of pressing metals, in which they use the "deforming gasket between the press washer and the pressed ingot", taken as an analogue (I. Perlin, Theory of metal pressing. M., "Metallurgy", 1964, pp. 106-109). This method is mainly recommended for pressing "such metals and alloys that are weakly oxidized and weld well" (for example, aluminum and some of its alloys, although its use for pressing difficultly deformed metals is not ruled out). In this case, deformable gaskets (technological press washers) are used. The method involves the manufacture of the rear convex end face of the workpiece and the concave surface of the front end of the deformable gasket. The calculation of the geometry and processing of the ends of the workpiece and the deformable gasket is a complex technological task and is approximate. In addition, this calculation does not take into account the influence of the geometric parameters of the tool - the matrix and the press washer, as well as the adhesion of the workpiece metal and the deformable gasket.

There is also a method of extruding profiles of dissimilar metals, taken as a prototype (Patent RU 2228810 C1, 7B21C 23/08, application 2002129669/02, 04.11.2002. Smirnov V.G. (RU), OJSC Verkhnaya Salda Metallurgical Production Association (RU) "The method of pressing profiles"). However, this technical solution can be used only with a certain ratio of the mechanical properties of the pressed workpiece and the technological washer. In addition, the inner cavity of the technological washer is made on a spherical surface, which presents technological difficulties. In addition, this design of the technological washer is not linked to the design of the tool - the matrix and the press washer. This pressing method does not exclude the adhesion of the workpiece metal and the technological washer, which significantly complicates the process due to the difficulty associated with separating the pressed profile from the metal of the press residue into which the metal of the technological washer was transformed.

The objective of the invention is to increase the yield when pressing a bar stock due to the absence of delamination of the metal and the formation of a press residue.

The problem is solved in that the method of manufacturing a bar stock of metal includes the installation of a pre-heated bar stock, a metal technological washer and a press washer in the press container, pressing and pressing the blank. In this case, a bar stock with a diameter equal to the diameter of the technological washer is used. Before heating the bar stock, the rear end face is pretreated on a truncated cone with an angle at the apex equal to (1.0 ÷ 1.5) the angle of the conical matrix, and on the surface of the technological washer contacting the bar blank, a depression is made with a surface similar to the contact surface of the pressed workpiece .

In the present invention, the geometric parameters of the rear end of the workpiece, the front end of the technological washer, the molded product and the main technological tool, the matrix, represent a single whole operation for pressing the workpiece.

The matrices used in the proposed process have a lead α = (90-130) °. The angle of the convex part of the rear end of the pressed billet is equal to 1.0 ÷ 1.5 of the matrix angle, i.e. approximately 120 °. Accordingly, the angle of the conical concave part of the technological washer has the same value, and the diameter of the small base is equal to the diameter of the pressed product. The pressing of the bar stock at the final phase of pressing and the formation of the press residue from the metal of the technological washer is illustrated in the drawing.

It is known that during pressing, until the formation of a press residue, laminar outflow of metal occurs, i.e. the linear speed of different points of the cross section of the workpiece in the pressing direction is the same. However, at the last stage of pressing during the formation of the press residue, this condition is violated. The outer layers, as in more difficult conditions (cooling, a longer path to the matrix point), are inhibited, and the central layers of the metal, as warmer and have a shorter path to the matrix point, are ahead of the peripheral layers, which leads to delamination of the metal and the formation of press weights.

In the proposed technical solution, this drawback is eliminated due to the fact that the back end of the workpiece is made conical. This increases the length of the path passing the center point "C" to the point of the conical matrix. As can be seen from the presented figure, A'C> A'B '. This condition can be satisfied when the angle of the conical part of the rear end of the workpiece, and therefore the angle of the conical concave end of the technological washer, is equal to 1.0 ÷ 1.5 of the angle of the conical matrix.

The metal of the technological washer, moving along the conical part of the matrix, settles and expands, displacing the metal of the workpiece in the radial direction. By pressing force, this metal moves in the direction of the matrix point. Thus, different cross-sectional points, despite different linear velocities, will approach the matrix point simultaneously.

For better separation of the workpiece metal and the material of the technological part, a layer of a substance can be applied to the surface of the rear end of the workpiece and the surface of the technological washer in contact with it, which facilitates the separation of the pressed product from the material of the technological washer.

The pressing can be carried out in such a way that when a press residue is formed from the metal of the technological washer, the time of metal movement to the matrix point of the peripheral point is equal to the time of metal movement to the matrix point of the central point of the back end of the workpiece.

The operation of the technological washer is illustrated in Figure 1.

Fig. 1 - Stages of extrusion of the rear end of a profile using a technological washer.

Fig. 1 (a) - initial; Fig. 1 (b) - intermediate; Fig. 1 (c) - final. 1 - pressed product; 2 - matrix; 3 - metal zone of the technological washer designed to press out the metal of the workpiece; 4 - metal zone of the technological washer from which the press residue is formed; 5 - a press washer; 6 - postmark.

Full extrusion of the metal of the workpiece allows you to use cheaper material as the metal of the technological washer compared to the metal of the workpiece.

The method can be used for any alloys (based on Al, Mg, Ti, Ni, etc.) and is easier to manufacture than the method adopted for the prototype.

In order to verify the correctness and performance of the proposed method of pressing it was tested. Pressed rods with a diameter of 18 to 60 mm from titanium alloy on 2000 t and 5000 t presses using billets of 125, 145 and 265 mm. All experiments gave a positive result. The yield after trimming the ends averaged 98% (see table No. 1).

Table number 1 No., No. Diameter of pressed rod, mm Diameter of the used workpiece, mm Yield,% one eighteen 125 97.0 2 53 265 98.0 3 60 125 97.5 four 60 145 99.0 Average ≈98.0

Claims (3)

1. A method of manufacturing a bar stock of metal, comprising installing a pre-heated bar stock in a press container, a metal technological washer and press washer, prepressing and pressing the workpiece, characterized in that a bar stock with a diameter equal to the diameter of the technological washer is used, and before heating of the rod billet, its rear end face is pre-treated on a truncated cone with an angle at the apex equal to 1.0 ÷ 1.5 of the angle of the conical matrix, and on contact with the rod billet the surface of the technological washer perform a cavity with a surface similar to the contacting surface of the pressed workpiece. 2. The method according to claim 1, characterized in that a layer of a substance is applied to the surface of the rear end of the bar stock and the surface of the technological washer in contact with it, which prevents contact welding during pressing. 3. The method according to claim 1, characterized in that the pressing is carried out in such a way that, when a press residue is formed from the metal of the technological washer, the time of movement of the metal to the point of the matrix of the peripheral point is equal to the time of movement of the metal to the point of the matrix of the central point of the rear end of the workpiece.