SU1574308A1 - Method of extruding low-ductile metals and alloys and tool for effecting same - Google Patents

Abstract

The invention relates to the processing of metals by pressure, in particular to a method of pressing low-plastic metals and alloys and an instrument for its implementation. The aim of the invention is to improve the quality of press products by reducing the defectiveness of their surface. During extrusion of low-plastic metals and alloys, the separation of surface layers into streams is carried out in the area of the lead-in cone of the matrix 4 and is moved along the rotating spiral in the direction from the center by rotation from the actuator 6 of the matrix 4. The helical grooves are made on the surface of the lead-in portion of the matrix 4. The ratio of the axial speed of extrusion and the speed of rotation is chosen in the range of 0.5 ... 2.0 mm / rad. The punch 3 is used to extrude the blank from the container 1 through the point of the matrix 4. 2 sec. f-ly, 2 ill.

Description

1

The invention relates to the processing of metals by pressure, in particular to the technology of pressing low-plastic metals with scalping of the surface layer.

The aim of the invention is to improve the quality of extruded products by reducing the defectiveness of their surface.

Fig. 1 schematically shows a pressing tool; figure 2 is the same, top view.

The tool contains a container 1, in the lower part of which there is an annular waste collector 2, placed a punch 3 and a matrix 4 with spiral grooves 5 on the lead-in part coaxially with the container, the matrix has a rotational drive 6.

The method is carried out as follows.

A billet of low-ductile metal is placed in container 1. During the working stroke of punch 3, rotational drive 6 of matrix 4 is activated and punch 3 is used to extrude the workpiece from container 1 through the point of matrix 4. After the extrusion cycle is completed, the punch returns to its original position, the matrix is stopped, and the pressed product is removed and the resulting waste in the form of a scalped layer from the waste collection 2.

- The method and tool for its implementation was tested under conditions of a vertical press with a force of 160 tf during deformation of chromium alloy blanks in the manufacture of wire blanks.

Pressing was carried out from a container DK 40 mm of a billet of a low-plastic chromium alloy 100 mm high with a draw ratio p. 16. At the same time, the speed of movement of the punch is 10 mm / s, and the speed of rotation of the die with an individual drive was varied in the range of 500 rpm; 100 rpm; 50 rpm (which approximately corresponded to 50 rad / s; 10 rad / s; 5 rad / s).

Spiral grooves of 1.5 mm depth with a step of 36 mm were made on the lead-in conical section of the matrix. An annular waste receptacle with a diameter of 60 mm and a height of 43 mm was made at the bottom of the container; the gap between the container and the die was 1 mm.

Accumulating, surface layers were squeezed into a waste collector made in a container. The removal of the scalpable metal from the deformation zone was made through the gap between the container and the matrix. The presence of grooves on the surface of the lead-in area of the matrix intensifies the deceleration of the surface layers of the workpiece during the rotation of the matrix, promotes the movement of metal from the surface of the pressed workpiece in the direction opposite to the extrusion of metal. Making the grooves in the form of a spiral with an inclination to the generator surface of the matrix in the direction opposite to the direction of rotation of the matrix reduces the possibility of brittle tears of individual

crystallites of the workpiece Along with this, the proposed direction of the grooves contributes to the scalping of the surface layers of the metal of the workpiece, while the metal of the jacket moves along the grooves

the entry portion of the matrix in the direction opposite to the flow of the middle part of the workpiece. The ratio of the axial speed of the working stroke of the punch and the tangential speed of rotation of the die is due to

as follows: With respect to the axial speed of the punch movement (Vo - mm / s) and the tangential speed of rotation of the matrix (w rad / s) greater than 2 mm / rad, no scalping of the surface layers is observed along the workpiece, there is a partial shift of the surface layers of the metal along the tangential trajectory a big step about the length of the workpiece without separating the surface layers from the adjacent layers

This allows to intensify the development of surface and adjacent volumes of the workpiece, but at the same time does not provide scalping of the surface layers. Decrease Vo / (about 0.5 mm / rad

leads to a significant temperature heating of the surface layers of the workpiece due to the work of the matrix rotation. This in turn causes the appearance of overburden of local areas of the pressed metal,

the occurrence of deep surface cracks. In addition, an increase in the speed of rotation of the matrix reduces the contact friction and the deformable metal acquires a predominant axial direction of flow, a slip relative to the rotating matrix.

10 blanks were pressed. In all cases, scalping occurred.

surface layer 1.1 mm thick. After pressing, the rods were measured in diameter in 8 sections along the length of the finished products. No deviations from the geometric dimensions were observed, which indicated a uniform scalping of the surface layer. On the surface of the extruded rods, there were no traces of: fractures, small cracks that occurred in the original blanks

Compared with the prototype, the use of this method of pressing and the tool for its implementation allows the use of a pressing process with scalping the surface layer for a number of low-plastic metals and alloys, which in turn improves the quality of the pressed products and reduces the laboriousness of their production by replacing mechanical stress. These surface layers are removed during the pressing process.

The forced rotation of the die during the extrusion process makes it possible to slow down the flow of the surface layers of the workpiece relative to the inner ones, when it is extruded through the die due to a predominantly tangential shift of the surface layers, holding the metal of the scalping layer,

Claims (2)

1. Method of pressing low-plastic metals and alloys, including extrusion of the workpiece through a matrix having a conical feed and cylindrical 0 five 0 five calibrating areas, with simultaneous separation of the surface layers of the workpiece into streams, from l and h and n and so that, in order to improve the quality of press products by reducing the defectiveness of their surface, the separation of the surface layers into streams is produced the matrix cone of the matrix with their twisting in a spiral in the direction from the center, and the ratio of the axial speed of extrusion and the speed of twisting is chosen in the range of 0.5-2.0 mm / rad. 2. A tool for pressing low-ductile metals and alloys, containing a hollow container with an annular waste receptacle made therein and a matrix mounted concentrically to the container with a gap relative to its cavity, differing in that the matrix is mounted rotatably in the plane perpendicular pressure axis, and is provided with a drive for this rotation, with spiral grooves on the surface of the inlet portion of the die.